Respondent Norman Hess, Warden of the Oklahoma state penitentiary, appeals the grant of a writ of habeas corpus to Manuel Lee Runnels, a State of Oklahoma inmate. Runnels cross-appeals the denial of relief on several other issues presented below.
Runnels was convicted in an Oklahoma state court of first degree rape. See Runnels v. State, 562 P.2d 932 (Okl.Cr.1977), cert. denied, 434 U.S. 893, 98 S.Ct. 270, 54 L.Ed.2d 179 (1977).1 Following the exhaustion of his state remedies, Runnels brought this action for the issuance of a writ of habeas corpus. The District Court granted the petition, finding/ruling that the prosecutor abridged Runnels’ privilege against self-incrimination by commenting on his failure to testify in his own behalf.
The issues presented are whether Runnels’ (1) constitutional rights were abridged by the prosecutor’s comment on the invocation of his privilege against self-incrimination; (2) procedural default in the state trial court precludes federal habeas corpus relief on his Fifth Amendment claims; (3) right to due process of law was abridged by the prosecutor’s use of false testimony; and (4) was denied effective assistance of counsel.
Privilege Against Self-Incrimination
A.
Hess argues that the prosecutor did not impermissibly refer to Runnels’ invocation of his Fifth Amendment privilege against self-incrimination. We disagree.
In reviewing a state prosecutor’s conduct in a habeas corpus action, we are precluded from applying the broad supervisory powers available on direct review. Donnelly v. De Christoforo, 416 U.S. 637, 94 S.Ct. 1868, 40 L.Ed.2d 431 (1974); Soap v. Carter, 632 F.2d 872 (10th Cir. 1980); Young v. Anderson, 513 F.2d 969 (10th Cir. 1975). Rather, habeas corpus relief is available only when the state has “violated some right . . . guaranteed by the Fourteenth Amendment.” Cupp v. Naughten, 414 U.S. 141, 146, 94 S.Ct. 396, 400, 38 L.Ed.2d 368 (1973). See also: Donnelly v. De Christoforo, supra, 416 U.S. at pp. 642—643, 94 S.Ct. at 1871.
Prosecutorial comment in a state criminal trial upon an accused’s failure to testify violates the self-incrimination clause of the Fifth Amendment and the Fourteenth Amendment. Griffin v. California, 380 U.S. 609, 85 S.Ct. 1229, 14 L.Ed.2d 106 (1965). This occurs where the prosecutor’s argument “was manifestly intended or was of such character that the jury would naturally and necessarily take it to be a comment on the failure of the accused to testify.” Knowles v. United States, 224 F.2d 168, 170 (10th Cir. 1955).
*1362Our decisions have distinguished between prosecutorial statements implying guilt or challenging credibility, and those relating to an accused’s failure to testify. For decisions in the first category, see United States v. Bridwell, 583 F.2d 1135 (10th Cir. 1978); United States v. Walton, 552 F.2d 1354 (10th Cir. 1977), cert. denied, 431 U.S. 959, 97 S.Ct. 2685, 53 L.Ed.2d 277 (1977); United States v. Bennett, 542 F.2d 63 (10th Cir. 1976), cert. denied, 429 U.S. 1048, 97 S.Ct. 757, 50 L.Ed.2d 763 (1977); United States v. Bishop, 534 F.2d 214 (10th Cir. 1976); Sanchez v. Heggie, 531 F.2d 964 (10th Cir. 1976), cert. denied, 429 U.S. 849, 97 S.Ct. 135, 50 L.Ed.2d 122 (1976); United States v. Fancutt, 491 F.2d 312 (10th Cir. 1974); United States v. Sawyer, 485 F.2d 195 (10th Cir. 1973), cert. denied, 415 U.S. 978, 94 S.Ct. 1566, 39 L.Ed.2d 874 (1974); United States v. Hodges, 480 F.2d 229 (10th Cir. 1973); United States v. Lepiscopo, 458 F.2d 977 (10th Cir. 1972); United States v. Reid, 415 F.2d 294 (10th Cir. 1969), cert. denied sub nom. Jones v. United States, 397 U.S. 1022, 90 S.Ct. 1261, 25 L.Ed.2d 531 (1970); and Ruiz v. United States, 365 F.2d 103 (10th Cir. 1966) (implying guilt or commenting on the evidence). For decisions falling in the second category, see United States v. Gilliland, 586 F.2d 1384 (10th Cir. 1978); Deats v. Rodriguez, 477 F.2d 1023 (10th Cir. 1973); United States v. Arnold, 425 F.2d 204 (10(h Cir. 1970); Doty v. United States, 416 F.2d 887 (10th Cir. 1968), vacated as to Epps only, 401 U.S. 1006, 91 S.Ct. 1247, 28 L.Ed.2d 542 (1971); United States v. Nolan, 416 F.2d 588 (10th Cir. 1969), cert. denied, 396 U.S. 912, 90 S.Ct. 227, 24 L.Ed.2d 187 (1969); and, Collins v. United States, 383 F.2d 296 (10th Cir. 1967) (commenting on invocation of Fifth Amendment privilege). Statements in the first category do not automatically call for reversal of the conviction; however, remarks made relative to an accused’s failure to testify normally do.
The fine line between what is permissible argument in this area is not always bright. Here, however, the prosecutor’s arguments crossed the limits of permissible conduct. We must agree with the Oklaho- ■ ma Court of Criminal Appeals that a “significant portion of the prosecutor’s closing argument, when taken as a whole, improperly emphasized the defendant’s failure to testify.” Runnels v. State, supra, at p. 937. The District Court’s assessment of the remarks summarizes our views:2
In this case, the statements of the prosecutor in his closing argument were not limited to a single reference to uncontradicted testimony. His statements referred individually to each item of evidence offered by the prosecution, and on two occasions, to the act itself. In the facts of this case, no person other than the defendant could have testified in contradiction of the testimony of the prosecutrix with regard to the act itself or with regard to the issue of force and the fear expressed by her. Fonzell Hamilton was called as a state’s witness and testified to the actions and occurrences which led up to the act itself. His testimony tended to corroborate that of the prosecutrix on certain of the force and fear aspects, but could not go to the act itself, as he was not present when it occurred. Cross-examination of this witness was directed primarily to the credibility of the prosecutrix and brought out certain inconsistencies and contradictions in her testimony, including her consent to have sexual relations with the witness and the use of marijuana by the witness, the prosecutrix and petitioner on the night in question. Petitioner’s only witness was the girl-friend of the petitioner, whose testimony added little or nothing to the evidence of events which took place on the evening in question. Her testimony, however, did bring out certain additional contradictions and inconsistencies in the testimony of the prosecutrix, particularly her testimony as to her chastity prior to the alleged rape.
R., Yol. I, p. 85.
*1363Had it been apparent on the record that the critical facts at the time of penetration could have been controverted by someone other than the accused, the argument would not have been objectionable. However, no one but Runnels could have contradicted the prosecutrix. Thus, the innuendo was sufficiently plain, as was the error.3 Doty v. United States, supra.
B.
Despite the constitutional error, Hess contends that federal habeas corpus relief is not available. He argues that Runnels’ failure to object at trial constituted independent, adequate state procedural grounds for the state court’s resolution of the Fifth Amendment claims.
Error at trial not objected to, in contravention of state contemporaneous objection rules, is unreviewable in habeas corpus proceedings absent a showing of cause for non-compliance and prejudice. Ulster County Court v. Allen, 442 U.S. 140, 99 S.Ct. 2213, 60 L.Ed.2d 777 (1979); Wainwright v. Sykes, 433 U.S. 72, 97 S.Ct. 2497, 53 L.Ed.2d 594 (1977); Francis v. Henderson, 425 U.S. 536, 96 S.Ct. 1708, 48 L.Ed.2d 149 (1976).4 The only exception occurs where “neither the state legislature nor the state courts indicate that a federal constitutional claim is barred by some state procedural rule.” Ulster County Court v. Allen, supra, 442 U.S. at p. 154, 99 S.Ct. at 2216. The exception does not apply here. The Oklahoma Court of Criminal Appeals clearly refused to reach the assignment of error on state procedural grounds. Runnels v. State, supra, at p. 937.
Initially, we note that Oklahoma does have a fundamental error exception to the contemporaneous objection rule. See Smith v. State, 599 P.2d 413 (Okl.Cr.1979), cert. denied, 444 U.S. 1022, 100 S.Ct. 681, 62 L.Ed.2d 654 (1980); Russell v. State, 528 P.2d 336 (Okl.Cr.1974); Neal v. State, 506 P.2d 936 (Okl.Cr.1973). Some have read Wainwright v. Sykes to allow complete federal review under these circumstances. Our interpretation of Wainwright v. Sykes differs. The Sykes rule was designed to avoid the effect of Fay v. Noia, 372 U.S. 391, 83 S.Ct. 822, 9 L.Ed.2d 837 (1961)— which encouraged “sandbagging” on the part of defense lawyers, “who may take their chances on a verdict of not guilty in a state trial court with the intent to raise their constitutional claims in a federal habeas court if their gamble does not pay off.” Wainwright v. Sykes, supra, 433 U.S. at p. 89, 97 S.Ct. at 2508. Carving out fundamental error exceptions to Sykes would seriously undermine its force. As a panel of the Court of Appeals, we are not empowered to do so. Accord: Hockenbury v. Sowders, 620 F.2d 111 (6th Cir. 1980), opinion on rehearing, 633 F.2d 443 (6th Cir. 1980).
Sykes dictates that cause and prejudice must be shown in order to obtain federal habeas corpus relief. With that dictate firmly in mind, we now turn to an examina*1364tion of those elements.5 Implicit within our holding of prosecutorial error is a finding of prejudice. The magnitude of the error in this case rises to a denial of a fundamental right.
The precise makeup of the cause prong of Sykes has not been detailed by the Supreme Court. Mr. Justice Stevens has indicated that such factors as the competence of counsel and the procedural context in which the waiver occurred may bear on the determination. Wainwright v. Sykes, supra, 433 U.S. at p. 96, 97 S.Ct. at 2511 (Stevens, J. concurring). Subsequent decisions have adopted these factors. See Tyler v. Phelps, 622 F.2d 172 (5th Cir. 1980).
While we elect not to paint with a brush as broad as the Tyler court, we nevertheless adopt much of its reasoning. We agree that in some instances “ineffective counsel, short of that necessary to make out a Sixth Amendment claim, will satisfy the ‘cause’ prong.” Id. at p. 177. This discourages “sandbagging”, while affording relief from “erroneous, nontactical decisions by counsel” resulting in prejudice. Id. See, e. g., Rachel v. Bordenkircher, 590 F.2d 200 (6th Cir. 1978) (affidavits by defense counsel showed inexperience, inattention and lack of knowledge of applicable law).
The District Court impliedly found the cause element to be satisfied. We, however, are unable to find any facts in the record bearing on defense counsel’s reasons or cause for noncompliance with the Oklahoma contemporaneous objection rule. Accordingly, it is not clear whether the failure to object resulted from a tactical decision. Proof of cause for noncompliance is essential; mere speculation that it existed is not enough.
Further complication arises from the District Court’s finding/conclusion that “[cjounsel’s representation of petitioner herein was competent and effective throughout and his failure to timely object to the prosecutor’s improper comments does not render his representation constitutionally ineffective.” R., Vol. I, p. 88. Cause for non-compliance and ineffective assistance of counsel are patently intertwined.
Rather than bluntly deny relief, Lewis v. Cardwell, 609 F.2d 926 (9th Cir. 1979), we will remand for reconsideration of the cause element, keeping in mind its interface with the ineffective assistance of counsel claim. Tyler v. Phelps, supra; Hockenbury v. Sowders, supra6 The remand is limited to reconsideration of these two areas — neither of which we now intimate views on their merits. The Sykes rule cannot be circumvented if the cause element is not established. The Sixth Amendment claim may be reexamined in light of intervening decisions. See Dyer v. Crisp, 613 F.2d 275 (10th Cir. 1980), cert. denied, 445 U.S. 945, 100 S.Ct. 1342, 63 L.Ed.2d 779 (1980).7
Remaining Contentions
Having reviewed the perjured testimony and knowing use of false evidence claims, *1365we find them unpersuasive. Similarly, no error occurred in the District Court’s denial of Runnels’ request for an evidentiary hearing on these two issues.
VACATED AND REMANDED.
. The facts of the case are detailed in Runnels v. State, supra. They will be referred to only when necessary to illuminate the issues presented.
. Some of the remarks are reprinted at Runnels v. State, 562 P.2d, pp. 936-937.
. Judge Barrett does not believe that the prosecutor’s closing argument should be construed as comments on the failure of Runnels to testify. In my view these comments, under the circumstances of this record, more accurately describe the prosecutor’s conviction that the prosecutrix’s credibility relative to the alleged sexual attack is unchallenged and that her testimony was truthful. The remarks followed defense counsel’s strong attack on the prosecutrix’s credibility. As I view the matter, each of the areas of testimony referred to in the prosecutor’s remarks were areas covered by testimony of others. Fonzell Hamilton, who was present during the sequence of events leading to the actual alleged rape, corroborated the prosecutrix’s testimony that Runnels threatened her and physically abused her. A doctor testified as to the presence of sperm. Thus, I do not believe that the jury naturally and necessarily took the prosecutor’s language to constitute comment on the accused’s failure to testify.
. We see no difference between judicially created contemporary objection rules and statutorily created state rules.
. It is possible to argue that if prejudice to the petitioner is clear, cause for non-compliance with the procedural rule need not be shown. Sumner v. Mata, 449 U.S. 539, 548, 101 S.Ct. 764, 769, 66 L.Ed.2d 722 (1981) (“‘cause’ or ‘prejudice’ ” in dicta). However, this view has been rejected. Francis v. Henderson, supra; Cole v. Stevenson, 620 F.2d 1055, 1062, n. 7 (4th Cir. 1980) (en banc).
. The burden of proving the existence of legally sufficient cause for noncompliance with the Oklahoma contemporaneous rules rests with the Petitioner. A factual basis supporting the Petitioner’s position must be established on the record. Thus, an evidentiary hearing on the matter should be held. This will allow the District Court to provide specific reasoning for its decision and provide a sufficient record for appellate review.
. We agree with the dissent that “the state’s case was relatively weak.” Infra at p. 1368. It is precisely for this reason that remand is appropriate to determine whether there was cause for noncompliance with the state procedural rule.
The fourteen year old prosecutrix was directly impeached concerning her prior chaste conduct. A witness testified that she had inadvertently observed the prosecutrix and her boyfriend engaging in intercourse, prior to the rape, on the floor of the same room in which the witness was sleeping. Use of marijuana by the prosecutrix during the events leading to the rape was also uncovered.
*1365Given the damaging testimony and the weakness of the state’s case, defense counsel may well have been willing to take his chances on a verdict of not guilty, intending to raise constitutional issues if the gamble did not pay off.