Ordered that the judgment is affirmed, with costs.
The appellant's principal contention is that because of his mental condition he lacked the capacity to enter into the contract for the sale of the real property at issue. The burden of proving mental incompetence is on the party asserting it (see, Feiden v Feiden, 151 A.D.2d 889, 890; Matter of Gebauer, 79 Misc.2d 715, 719, affd 51 A.D.2d 643). We agree with the Supreme Court that the appellant failed to sustain his burden. The focus of the inquiry was whether the appellant was capable of comprehending and understanding the nature of the transaction at issue (see, Ortelere v Teachers' Retirement Bd., 25 N.Y.2d 196, 202; Aldrich v Bailey, 132 N.Y. 85, 89), or whether the appellant, due to his mental illness, was unable to control his conduct (see, Ortelere v Teachers' Retirement Bd., supra, at 203). The appellant's medical expert was unable to state with a reasonable degree of medical certainty that the appellant at the time of the transaction at issue would have been unable to understand the nature of the transaction and the consequences of his signing of the contract of sale. Furthermore, the Trial Judge found the appellant's testimony as to his mental condition lacked credibility. Due deference must be given to the Trial Judge's assessment of credibility as he is in the best position to evaluate the evidence and the credibility of witnesses (see, Matter of Liccione v John H., 65 N.Y.2d 826, 827; Roache v City of Mount Vernon, 160 A.D.2d 863). We perceive no basis in the record to disturb his findings and, accordingly, adopt the Supreme Court's conclusion that the burden of proving incompetency was not sustained. Thompson, J.P., Brown, Eiber and O'Brien, JJ., concur.