Sporting Kansas City kept up their perfect start to the Major League Soccer season as they edged out the Los Angeles Galaxy 1-0 for their fifth straight win, Kei Kamara getting the goal after 41 minutes.
New York Red Bulls thrashed Columbus Crew 4-1 to go second in the Eastern Conference, although they are already six points adrift of Kansas City.
Kenny Cooper and Thierry Henry each had a brace, Henry's goals coming either side of a late consolation for the Crew from Chad Marshall.
Real Salt Lake sit top of the Western Conference with 15 points from six matches after beating the Colorado Rapids 2-0. Alvaro Saborio put them ahead after 20 minutes and Edgar Espindola's 57th-minute strike wrapped up the points.
Wondolowski wins it for San Jose
The San Jose Earthquakes are three points behind with a game in hand after topping the Vancouver Whitecaps 3-1.
They trailed to Sebastian Le Toux's 49th-minute opener, but Chris Wondolowski's 68th-minute equaliser was the first of three San Jose goals inside ten minutes, as Alan Gordon and Wondolowski again turned it around.
Montreal Impact beat Canadian rivals Toronto FC 2-1 as Sinisa Ubiparipovic and Andrew Wenger put them on top before Danny Koevermans' late consolation for the visitors.
Chivas USA came from behind to overcome the Portland Timbers in Oregon, with Alejandro Moreno cancelling out Kris Boyd's early opener before Nick LaBrocca won it with eight minutes left.
DC United and the Seattle Sounders shared a goalless draw.