San Jose moved seven points clear on top of the MLS Western Conference on Wednesday, while LA Galaxy had to scramble for a point in Vancouver.
The Earthquakes headed into their home clash with Dallas holding a four-point buffer over Real Salt Lake, who had played one game more, and they increased their lead at the helm with a 2-1 victory.
Marvin Chavez gave the home side the perfect start at Buck Shaw Stadium when he fired them ahead after 12 minutes, and when Alan Gordon scored on the stroke of half-time the hosts were firmly in control.
Dallas fought back in the second half, but it was too late as a late goal from Colombian defender Hernan Pertuz proved mere consolation.
In Vancouver, the Los Angeles Galaxy could have given their play-off hopes a boost had they beaten the Whitecaps, but they were held to a 2-2 draw.
Goals from Gershon Koffie and former Celtic and Middlesbrough man Barry Robson put the Whitecaps 2-0 ahead inside of half an hour.
But the defending MLS champions emerged from the half-time break reinvigorated, and goals in the final 10 minutes from David Beckham and Jose Villarreal helped secure a point for Bruce Arena’s team, who remain in fifth spot in the Western Conference, four points behind Vancouver and Seattle.
In the East, New York Red Bulls closed to within a point of leaders Sporting KC courtesy of a 1-0 home win over Chicago Fire, with French star Thierry Henry scoring a brilliant winner on 71 minutes.
Henry adroitly controlled a lofted ball into the area on his chest before rifling a left-foot volley past Sean Johnson in the Chicago goal, with the ball cannoning in of the right-hand upright.
Sporting Kansas City, meanwhile, had their lead shrink to just one point after a brace from Calen Carr saw them slump to a 2-1 loss on the road to Houston Dynamo.
In other results, a 16th-minute goal from Miller Bolanos saw Chivas USA take a 1-0 win over Portland Timbers at The Home Depot Center, and the Eastern Conference’s bottom side, Toronto, enjoyed a rare victory, with second-half goals from Ryan Johnson and Andrew Wiedeman helping them come from behind at home to beat Colorado Rapids 2-1.
And Montreal Impact enjoyed a 2-1 triumph over New England Revolution in Quebec.