Sporting Kansas City extended their unbeaten run to six games with a 2-1 victory over Los Angeles Galaxy.
The Portland Timbers kept alive their faint hopes of making MLS play-offs with a 2-1 win over the Colorado Rapids.
Clint Dempsey made a successful return to MLS action with a goal as the Seattle Sounders beat the Portland Timbers 2-0.
Eddie Johnson sent DC United on their way to a third straight away win as they defeated the San Jose Earthquakes 2-1.
AC Milan have announced they are negotiating the sale of Brazilian forward Robinho to new MLS franchise Orlando City.