Honours were split in the Eastern Conference's top-of-the-table clash between New England and DC United, with the Revolution finishing with nine men.
Charlie Davies' opener late in the first half at the Gillette Stadium had the Revolution on track to claim top spot in the standings, but DC United equalised with 10 minutes to play via Jairo Arrieta in the 1-1 draw.
Davies tapped in the save from Juan Agudelo's header, with goalkeeper Bill Hamid unable to deny the Revolution twice in succession.
But the hosts lost control from literally that point on, Lee Nguyen earning a yellow in the little time remaining in first-half injury time from the restart.
Chris Tierney was then shown a straight red card in the 52nd minute, for a studs-up challenge on Chris Pontius.
Six minutes later, Nguyen received a second yellow to further agitate the home fans - as he threw an elbow into the face of Davy Arnaud.
Nine-man Revolution continued to attack, but they would finally be exploited for their numerical disadvantage - Arrieta on hand to punch home Taylor Kemp's cross in from the left in the 80th minute.
DC United (22 points) have a game in hand on New England (20).
The Colorado Rapids snapped a run of four straight draws, edging the Vancouver Whitecaps 1-0.
Lucas Pittinari's 51st-minute goal was enough for the Rapids to win for the first time in six outings, in all of which they have posted the lone strike.
The Whitecaps, meanwhile, missed the chance to reel in Western Conference leaders Dallas, who were beaten 2-1 at the Montreal Impact.
Seattle Sounders' 0-0 draw at home to Sporting Kansas City was enough to take them above the Whitecaps in second spot in the West, but a win would have sent them top of the standings.
Real Salt Lake were 2-0 winners over struggling New York City, while Toronto had a stunning Sebastian Giovinco strike to thank for their 1-0 victory over Portland Timbers.
