First-half goals from Marvin Chavez and Alan Gordon were enough for Western Conference leaders San Jose Earthquakes to record a nervy win over Dallas at Buck Shaw Stadium.
Dallas started brightly but, after Matt Hedges had twice gone close with headed efforts for the visitors, Chavez opened the scoring in the 12th minute with a simple finish following a Shea Salinas cross.
The goal seemed to knock the stuffing out of Dallas and the game looked to be effectively over in first-half stoppage time when Gordon dispatched Sam Cronin's whipped delivery into the bottom right corner with a bullet header.
San Jose should have extended their advantage on the hour-mark when Brek Shea handled in the penalty area, giving Chris Wondolowski the chance to score from 12 yards.
However, Dallas goalkeeper Kevin Hartman made a superb save, pushing Wondolowski's low spot-kick around his post for a corner.
Hernan Enrique Pertuz Ortega pulled a goal back in the 89th minute and Dallas were then given a golden chance to snatch a creditable draw in stoppage time when Simon Dawkins gave away the game's second penalty after hacking down Zach Lloyd.
The match was briefly delayed as Lloyd received treatment and when play resumed Jair Benitez lashed his left-footed effort over the bar.