MONTREAL - The fans turned out to Olympic Stadium in droves and the Montreal Impact responded.

Eduardo Sebrango scored twice as the Impact fed off the noise and enthusiasm of 55,571 spectators at Olympic Stadium for a stunning 2-0 victory over Santos Laguna of Mexico in the first leg of their CONCACAF Champions League quarter-final on Wednesday night.

The Impact will take a two-goal advantage into the second leg of the two-game, total goals series March 5 in Torreon, Mexico, where the stadium holds 30,000.

"We needed a boost because it was our first competitive game since October, and they gave us a big boost," Impact coach John Limniatis said of the fans, most of them dressed in Impact blue and white. "They really helped us with their energy."

The veteran Sebrango, signed in the off-season from Vancouver, worked a give-and go with Roberto Brown, slid between two defenders and blasted a shot past goalkeeper Oswaldo Sanchez in the fifth minute to a huge roar from the stands, where many fans were still making their way to their seats.

Sebrango said the shot went off a Santos defender, but "I'll take it."

In the 77th minute, defender Nevio Pizzolitto's long ball down the middle on a free kick was headed into the box by Brown and went over a Santos defender. Sebrango jumped and just beat Sanchez to the ball to head it in and give Montreal a commanding lead in the home-and-away series.

"This is the top of my career," Sebrango added. "I didn't know I could play in this tournament when I signed with Montreal because I played in Vancouver last year.

"So this is a bonus -- to score and play in front of 55,000. Hopefully we'll win (the series) and it'll be ever bigger next time."

It was the largest crowd for soccer at the domed facility since 58,000 fans took in a playoff game with he Montreal Manic of the defunct North American Soccer League and Chicago Sting in 1982.

The Impact, forced indoors by winter weather, won over thousands of new fans by reaching the quarter-final and the huge crowd was seen by soccer officials as a breakthrough for the sport in hockey-mad Canada.

A quarter-final Tuesday night in Houston drew just over 10,000 fans as the Dynamo tied 1-1 with Atlante of Mexico in their first leg.

"Nothing's over," cautioned Limniatis. "It's 2-0, but we all know the game in Mexico will be extremely tough.

"They'll have a lot of energy."

The Impact will play an exhibition game against Dynamo in Houston on Saturday before heading to Torreon, which is in northern Mexico not far from the Texas border.

Santos coach Daniel Guzman, who said his team struggled on the synthetic surface at the Big O, predicted a much different match on grass in Mexico.

"The Impact took advantage of our mistakes and we weren't alert enough," Guzman said through a translator. "But we'll learn from this and I have no doubt we will make it up in the return leg."

The Santos side also had trouble containing Sebrango and Brown, both quick, tall and strong on crosses or lobs into the middle.

The Mexicans like to move the ball in quick, short passes, but a rare long ball nearly tied it in the seventh minute. Impact goaltender Matt Jordan just managed to sweep the ball away from star striker Christian Benitez, who three minutes later had another chance but shot over the bar. Benitez was a threat to score all night.

The Impact played tight defence around its box, but fans gasped as defender Pedro Quinonez curled a free kick to the left post that forced Jordan to make a diving save in the 53rd minute.

The defence only tightened further when the home side went up by two goals.

"Turf is not the best surface for pro players with all the changes in direction," said Impact midfielder Sandro Grande. "It takes a toll on your body.

"But it's difficult for us, too. We have a new (outdoor) stadium with beautiful green grass and we can't wait to get on it. I don't think they missed any passes or goals because of the turf. It's just as hard for us. But if we get 55,000 out to Olympic Stadium well, let's play on turf every time."

The Impact normally play next door to Olympic Stadium at 13,000-seat Saputo Stadium, which they fill regularly for United Soccer Leagues matches.

It was Montreal's first real match since its final game of the Champions League group stage against Atlante on Oct. 28. The team regrouped in early January for training camp, which included a three-week stay in Italy, where they played five exhibition matches against lower-division clubs.

Montreal got into the inaugural CONCACAF Champions League by edging Toronto FC and the Vancouver Whitecaps for the Voyageurs Cup in the Nutrilite Canadian Championship last spring.

They then beat Real Esteli of Nicaragua in a playoff to reach the group stage, where they qualified for the quarter-finals by finishing second in their four-team group to Atlante.

Olympic Stadium's biggest soccer crowd ever was more than 70,000 for the 1976 Olympic final between East Germany and Poland.

In Wednesday's other CONCACAF Champions League quarter-final first leg, CD SC Cruz Azul beat Pumas UNAM 1-0 in Mexico City.

Should Montreal win its quarter-final, it will play again at the Big O in the semifinals, with the first leg between March 17 and March 19 and the second April 7-9. The home and away final is to run April 21-23 and April 28-30.

The winner advances to the FIFA Club World Cup in December in the United Arab Emirates. The 2008 champion was Manchester United.

The two yellow cards shown by American referee Terry Vaughn went against Montreal, to Brown in the 45th minute and substitute Felix Brillant in the 90th minute.

Montreal was without team captain Mauro Biello (collarbone), defender Stefano Pesoli (knee) and midfielder Simon Gatti (thigh).