The Impact were held to a 0-0 draw away at Philadelphia Union, while both Red Bulls and Sporting had 2-1 victories which sees the three sides level on 42 points.
Montreal have two games in hand on their Conference rivals, but would likely have rued failing to score for their first league game in six.
Red Bulls finished with 10 men but held on for a 2-1 win at home to DC United.
Lloyd Sam struck on eight minutes for the hosts in New York, only for Nicholas DeLeon to equalise for DC.
Australia international Tim Cahill then headed home what proved to be the winner on 38 minutes.
Ibrahim Sekagya was given his marching orders on 73 minutes, but Red Bulls held on for the three points.
Sporting Kansas were fired to a 2-1 win late by Graham Zusi's 88th-minute winner over the Colorado Rapids.
Western Conference leaders Real Salt Lake thrashed 10-man Portland Timbers 4-2, while Toronto and New England drew 1-1.
The Seattle Sounders went third in the West, after a brave 1-0 away win over Columbus Crew - with the Sounders playing 83 minutes with 10 men after an early dismissal to Leonardo Gonzalez.
Three points above Seattle in second spot are the Los Angeles Galaxy, who powered to a 3-0 win courtesy of a Robbie Keane brace in addition to the opening goal from Landon Donovan.
The Houston Dynamo nabbed a point at the death in a 1-1 draw on the road at Chicago Fire, while the Vancouver Whitecaps similarly fought back from a two-goal deficit to earn a 2-2 result at home to Chivas USA.
