Mike Magee grabbed a brace, but will regret failing to get a third as Montreal left Toyota Park with a point in a roller coaster match.
The Impact took the lead with the first half's only goal. Davy Arnaud found Marco Di Vaio with an excellent through ball, and the veteran made a nice touch and cut between two defenders to finish easily and score his 19th goal of the season, the lead in the MLS Golden Boot race.
But Mike Magee wasn't ready to let the Italian escape withthe crown so easily. Alex's deflected shot fell pefectly for the forward, and he poached his goal well from close range to equalize in the 57th minute.
He then scored a second in the 74th minute, stripping goalkeeper Troy Perkins after an error with the ball at his feet and poking home as the keeper tried desperately to recover.
Troy Perkins' was lucky not to give away another goal a few minutes later. He connceded a penalty when he was judged to have taken out Patrick Nyarko's feet, but to his relief, Magee's attempt for the hat trick was smashed off the crossbar.
Magee went close again in the 82nd. Chris Rolfe's shot went off the post, drawing Perkins out of position,and when the ball came back to Magee he seemed certain to score with his low shot until Hassoun Camara cleared the effort off the line.
Magee's inability to finish off the Impact would come back to haunt him in the 87th minute. MArco Di Vaio was dispossessed in the box, but Jeff Larentowicz's clearance deflected off Jalil Anibaba's back and allowed youngster Maxim Tissot to score his first professional goal.
Chicago (11-12-7) misses an opportunity to move into the playoff spots, and is now two points behind Philadelphia. Montreal (13-9-7) is in third, slipping out of the Supporters' Shield picture.