— Order, Supreme Court, Bronx County (Bertram Katz, J.), entered May 8, 1989, which, in relevant part, denied defendant’s motion seeking to compel plaintiff to serve a further bill of particulars, unanimously affirmed, with costs.
A party may be required to particularize an element of his claim or defense on which he bears the burden of proof (Bounds v Mutual of Omaha Ins. Co., 37 AD2d 1008). We see no error in refusing to compel plaintiff to particularize matters which would be elements of a claim grounded on an alternative theory, where plaintiff has never embraced that alternative theory and where such in fact forms the basis of defendant’s first affirmative defense. The trial court has ample power to prevent surprise and prejudice should plaintiff alter his position and later attempt to introduce proof on the alternative theory now abjured (see, CPLR 3042). Concur— Milonas, J. P., Rosenberger, Ellerin and Rubin, JJ.