Landon Donovan scored the winner from the penalty spot as the Los Angeles Galaxy beat DC United 2-1.
Western Conference leaders the Galaxy went ahead when striker Edson Buddle netted from close range after 38 minutes, but United, who stand bottom of the Eastern Conference, grabbed an equaliser in the 54th minute when Trinidadian Andy Najar headed in.
However USA forward Donovan had the deciding say, converting a penalty four minutes later after a handball by Julius James.