Sporting Kansas City maintained its perfect record through three games with a 1-0 win over Toronto FC on Sunday.
Toronto FC nearly took the lead after the hour mark when Sebastian Giovinco played through Tsubasa Endoh, but Tim Melia blocked his shot and it caromed off the crossbar.
Giovinco followed up that chance by dancing through SKC defenders, but his toe poke flew over the bar.
And soon after, Brad Davis scored his first goal for Sporting, though Toronto players were left shouting for a whistle after Davis sent defender Justin Morrow to the ground in the buildup.
Sporting's Roger Espinoza saw a straight red card with six minutes remaining for a challenege on Marco Delgado, but the hosts were able to hang on to become the only MLS team with a perfect three wins to start the season.
United States striker Jozy Altidore made his season debut for Toronto FC as a 77th-minute substitute ahead of this week's World Cup qualifiers.
D.C. United rallied to salvage a 1-1 draw with the Colorado Rapids.
Both teams had chances to open the scoring, with Colorado's Kevin Doyle hitting the post from a seated position in the first half, and Lamar Neagle missing a volley from point-blank range for United.
The Rapids found the breakthrough in the 69th minute when Dillon Powers headed in a corner kick.
But D.C. found an equalizer 10 minutes from time when Zac MacMath misplayed a cross and Fabian Espindola cleaned up the loose ball.
MacMath's error was the 14th time he failed to handle a cross in the past five seasons, the most of any goalkeeper in MLS in that time.
C.J. Sapong scored twice as the Philadelphia Union cruised past the 10 men of the New England Revolution 3-0 on Sunday.
The Union took the lead in the 18th minute when Sapong controlled the ball in the box and took a deflected shot that beat Bobby Shuttleworth at his near post.
It was 2-0 in the 34th minute after Warren Creavalle cut a pass back for Sapong to score in the center of the box.
Lee Nguyen nearly pulled the Revs back in the game but his free kick hit off both posts and somehow stayed out.
But hope of a comeback ended in the 37th minute when Je-Vaughn Watson was sent off for a dangerous tackele on Roland Alberg.
The scoreline would have been much worse if not for the work of Shuttleworth, who stopped two penalties. He saved Ilsinho's effort in first-half stoppage time and then kicked away Sebastien Le Toux's try in the 79th minute.
Le Toux did turn in a pass from Leo Fernandes in the closing moments to seal the points.