The West Ham defender, 24, admitted attacking the woman at Faces Nightclub in Ilford, on October 17 last year.
Da Costa hobbled into the dock at Snaresbrook Crown Court on crutches sporting a plastic cast on his right lower leg after clashing with Darren Bent in Saturday's home defeat to Aston Villa.
Not much to smile about: A glum-faced Manuel Da Costa, 24, admitted attacking a woman at Faces Nightclub in Ilford, on October 17 last year. The West Ham defender will now face trial in September
He admitted common assault but denied a sexual assault on the same woman and was ordered to stand trial in September.
Dressed in a black suit and white, open necked shirt he spoke only to confirm his name and enter his pleas.
The Portugal under-23 international, arrested on October 19 last year, has made just 13 Premiership appearances for the Hammers so far this season.
Clash: Da Costa was left with an injury to his lower leg after colliding with Darren Bent in Saturday's home defeat to Aston Villa
The defender arrived at the Upton Park club on a three-year contract in August 2009 from Italian side Fiorentina, having previously played in France for AS Nancy and in Holland for PSV Eindhoven.
He has been capped 22 times by Portugal at under-20, under 21 and under-23 level.
Da Costa, of Docklands, east London, was remanded on conditional bail to stand trial on September 12.
He was ordered not to enter Faces nightclub and not to contact the complainant.
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