Marco Di Vaio scored his first goal for Montreal Impact as they beat New York Red Bulls 3-1 in the Eastern Conference.
Di Vaio got his first MLS goal in the 48th minute and there were also strikes from Davy Arnaud and Sanna Nyassi.
Thierry Henry scored his 11th goal of the season before Nyassi secured the win for Montreal in the 74th minute which dented New York's title hopes in the Eastern Conference.
Houston Dynamo closed to within one point of the leaders with a 2-0 win over Toronto for a fourth straight victory.
The Dynamo moved into second place as a result of the win which came with goals from Calen Carr and Brian Ching.
Jairo Arietta marked his MLS debut with two goals as Columbus defeated Sporting Kansas City 2-1.
The visitors went ahead in the eighth minute through Kei Kamara's header but Arietta, who joined the Crew from Costa Rican club Deportivo Saprissa, scored in the 17th and 34th minutes.
Columbus finished the match a man down after Cole Grossman was issued a straight red card in second half stoppage time for a foul on Graham Zusi.
The San Jose Earthquakes went two points clear in the Western Conference with a 1-1 draw against Chicago Fire. The Earthquakes extended their lead over Real Salt Lake thanks to a late strike from Stephen Lenhart.
Chris Rolfe had given visitors Chicago the lead in the first half before San Jose saw Lenhart equalise late on before the home side's Alan Gordon was sent off in the third minute of added time for a second yellow card.
Mike Magee scored in the 62nd minute as a Los Angeles Galaxy side without Landon Donovan and David Beckham beat FC Dallas 1-0.
The defending MLS champions were without the suspended Donovan and Beckham who has not returned to the United States since taking part in the opening ceremony at the London 2012 Olympic Games.
Osvaldo Alonso scored in the 66th minute as the Seattle Sounders won 2-1 to hand Colorado Rapids a sixth straight loss. Eddie Johnson scored in the first minute but Drew Moor replied two minutes later for the Rapids. Johnson then had a hand in the winning goal for Alonso.
Bottom side Portland Timbers were 1-0 losers against Chivas USA who scored the only goal through Danny Califf.