Maybe he was a closet Wilt Chamberlain.
if it is uncorroborated (#witnesses == 1) or only very loosely corroborated (#witnesses == ~1) then it would be a he-said-she-said, with the likely (to all concerned) outcome being defendedt held not liable.
however, if there are a large number of credible corroborating witnesses, then the outcome might be somewhat more problematic to predict.
IMHO, IANAL