MONTREAL — For a team of veterans playing a second playoff game in three days, the Montreal Impact showed plenty of life.

Matteo Mancosu got the only goal in the second half and the defence held off the New York Red Bulls' vaunted attack for a 1-0 victory Sunday in the opening match of their MLS Eastern Conference semifinal.

Montreal takes a one-goal lead into the second leg of the two-game, aggregate goals series next Sunday at Red Bull Arena in Harrison, N.J., where they have never won in seven visits.

But they had also never won in Washington before ousting DC United 4-2 in the knockout round on Thursday night.

"The first half, (the Red Bulls) had a lot of pressure," said the Impact's 37-year-old captain Patrice Bernier. "We expected it, but it wasn't easy.

"They wanted to play fast to get us unbalanced and tired because we played on Thursday. And I'm pretty sure they knew they were playing a team that's a bit older, but our will is a lot stronger than our fatigue. We weathered the storm and we waited to pounce when we had a chance."

The chance came in the 61st minute when Marco Donadel lofted the ball over the New York defence and Mancosu, without breaking stride, blasted a half volley under the crossbar to a roar from the 15,027 at Saputo Stadium. The Italian, who took the starting striker's job from Ivorian legend Didier Drogba, now has three goals in his first two MLS playoff matches.

The Red Bulls, who finished first in the conference, controlled much of the play and had the better chances overall, but lost for the first time in 20 games, including 16 MLS matches, since July 3.

They also head home with questions over their ability to score in the post-season. They were favourites last year when their attack went missing in a loss to Columbus in the conference final.

"At times we played well and were organized and then one play cost us, even though we had pretty good control of the match," said Red Bulls coach Jesse Marsch. "And even when we had good chances, we couldn't convert them.

"So we walk out of here without a goal, but we know it's only half time. There's a lot more to go in this series."

There are no secrets between the teams. Montreal knows New York will play a high pressure game built around league scoring leader Bradley Wright-Phillips and assist leader Sacha Kljestan, while the Impact will stay back, waiting for chances to counterattack.

Each side had a first-class scoring chance in a physical first half. Wright-Phillips was in alone early but saw goalie Evan Bush make a vertical leap to grab his chip shot.

Just before the intermission, Ignacio Piatti won a ball on the left flank and saw his high cross headed just wide by Mancosu.

After Mancosu's goal, the Red Bulls pushed hard and missed a glittering chance in added time as Bush made a diving save and Wright-Phillips hit the rebound just wide.

"We knew they would be on top of the game and try to press us high," said Bush. "We were prepared for that.

"Dictating the tempo does not always mean being on top of the game. It means playing the game at the pace you want to play at. We were able to do that. They had the ball more than we did, but we were able to get in behind and get chances."

The Impact are in the same position as a year ago, when they won the first game of the conference semifinal at home against Columbus 2-1. The difference is that the Crew walked off with an away goal in their pocket, a key tiebreaker, and then won the series on home turf.

Montreal looked like it may not even make the playoffs in early September, but has gone 4-1-1 in its last six, including playoffs.

Each team had a player ask to be taken off — New York's Kemar Lawrence with a hamstring problem and Montrreal's Hernan Bernardello with a cramped calf — but both are expected to be ready for the next game. New York will be without forward Omer Damari, a substitute who was sent off in injury time after a hard slide into Calum Mallace.

The Impact were without Drogba for a third straight game. The striker has been recovering from a sore back, but Biello had hoped to have him available off the bench. Drogba was in the locker-room with his teammates after the match.