Dallas continued their bright start to the MLS season with a 1-0 win over the Los Angeles Galaxy on Saturday, while Chivas USA were beaten.
Schellas Hyndman's Dallas side moved six points clear atop the Western Conference with their hard-fought win in Texas.
George John scored the only goal of the game as Dallas recorded their fifth win in seven games.
It came after Galaxy defender Leonardo was sent off in the 61st minute and John headed in the winner after a goalmouth scramble from a corner three minutes before full-time.
As he ran to celebrate, the Dallas defender was struck by an object thrown from the crowd.
Chivas USA are six points adrift in the conference but have a game in hand after their 1-0 loss to the Colorado Rapids.
Deshorn Brown scored the only goal of the game from the penalty spot in the seventh minute.
The New York Red Bulls moved into fifth in the Eastern Conference thanks to their 2-0 victory against DC United.
In what was arguably their finest performance of the campaign, the Red Bulls went ahead through Thierry Henry, who curled a 25-yard effort into the bottom corner on 29 minutes.
Jamison Olave doubled their advantage seven minutes later, diverting in from close range.
Jack McInerney's 90th-minute equaliser earned the Philadelphia Union a 1-1 draw at home to Toronto, who had Robert Earnshaw open the scoring in the second half.
The winless Seattle Sounders played out a 0-0 draw against New England, while the Vancouver Whitecaps drew 0-0 at home to Real Salt Lake.