Jack McInerney, recently signed by the Impact (0-3-3), broke the ice with a goal in the 43rd minute, taking a pass from fellow forward Marco Di Vaio and driving the ball into the mesh off the left foot of goalkeeper Sean Johnson.
Quincy Amarikwa of the Fire (0-1-5) evened the score on the 54th minute, converting a corner kick from Mike McGee, reversing a trend in which Chicago has been victimized by set plays throughout the season.
The opening half of play provided very little to either enthuse or engage the crowd, as both sides played tentatively, neither side taking major chances in the early going.
Despite holding a marked edge in possession time and directing eight shots toward the goal to Montreal's three, the Fire came out of the first half trailing thanks to McInerney's goal.
More dangerous opportunities came in the 23rd minute, when McGee had his drive blocked by an Impact defender and the 37th, and when rookie Eric Miller stopped Nyarko's shot from just outside the six-meter box.
Nyarko received a caution following a collision with Perkins, the only booking made by referee Jose Carlos Rivero in the first half of the match, which ended with a 45th minute shot by McInerney that went wide on another feed from Di Vaio.