TORONTO — The Montreal Impact are hoping Saturday's upset win over one of the top clubs in MLS will provide a confidence boost with two months remaining in the regular season.

Ignacio Piatti scored the only goal that was needed as the Impact blanked Toronto FC 1-0, stunning the Eastern Conference leaders in the latest edition of the 401 Derby.

"The win is massive, obviously," said Impact coach, Mauro Biello.

"They're probably the best team in the league. They've been on a very good run here, they're scoring goals, they're defending well. We did a good job, we were organized, we didn't give them much space to break us down, especially in the first half."

Piatti's goal came in the 73rd minute. The Impact midfielder picked up a Dominic Oduro feed and beat a sprawling Alex Bono for his 14th goal of the season.

"I thought we played a good game away from home," said Oduro. "We were much disciplined. The whole idea was try to stop them as much as possible, stay compact, hit them on the counter and that's exactly what we did even though we were a man down. We fought very well."

Toronto had an excellent chance to tie the game in the 87th minute, but Tosaint Ricketts put his header off the side of the goal.

The win is Montreal's (9-7-10) first since Aug. 6 — a stretch of three games. It was also the Impact's first MLS victory at BMO Field, snapping an 0-3-3 stretch. With the three points, Montreal temporarily moves into a tie for fourth in the Eastern Conference.

The loss snaps Toronto's (12-8-7) stretch of five straight wins on home turf and the Reds' overall unbeaten streak at seven games. TFC remains the top seed in the East, but could be passed by New York City FC on Sunday.

"We gave up a goal in a situation where we should never give up a goal," said TFC coach Greg Vanney. "It's a goal kick where we should have plenty of numbers back to deal with it.

"Once you give up the goal too, (the Impact) no longer have any ambition to have to play. They're just going to sit 10 guys in their box."

Sebastian Giovinco left the game in the 67th minute favouring his right leg following a challenge from Kyle Bekker. Vanney said Giovinco had some "quad-region soreness" and will get re-evaluated on Sunday.

Impact forward Didier Drogba's night ended in the 55th minute due to a hamstring injury. Biello says he will be looked at again and didn't know the extent of the injury.

Things got heated between the two clubs in the 42nd minute after Impact midfielder Calum Mallice ran over TFC defender Steven Beitashour at midfield. Following an altercation between both clubs, Mallice was issued a straight red card while Toronto midfielder Marko Delgado was issued a yellow card.

"I thought we had numbers going forward, so I was trying to get the ball on our side as fast possible, get it down in play and the guy on their side was trying to do the opposite, trying to keep it away from two of us and we were both going pretty fast and just collided into each other," said Mallice.

"I re-watched it, and personally I still don't think it's a red card. In the moment I didn't think it was a red card. I hope the league can see that and agree."

The Canadian rivals meet for a third and final time on Oct. 16 in Montreal.