03/16/2015 04:50 EDT | Updated 05/16/2015 05:59 EDT

Goalkeeper Bush brings experience to Impact's first CONCACAF semifinal

MONTREAL - It used to be that non-league matches were reserved for the Montreal Impact's backup goalkeeper.

But with the Impact in the CONCACAF Champions League semifinals for the first time, it's become a prestige assignment for Evan Bush.

Bush, who took over from Troy Perkins as the No. 1 goalie midway through last season, will be the starter when the Impact will play host to Alajuelense of Costa Rica in the first leg of the two-game, total goals series on Wednesday night at Olympic Stadium.

As of Monday, 28,000 thousand tickets were sold.

"It's definitely different from the Canadian cup," Bush said Monday, recalling his first three MLS seasons in Montreal when about the only action he saw was in Amway Canadian Championship matches and CONCACAF group stage games. "This year maybe (backup) Erik Kronberg will get those games.

"It's a different scenario. At this stage, you want the guys out there that are most comfortable in those situations and most comfortable with what's trying to be done."

Kronberg, acquired in the off-season, is not eligible to play because he already appeared in the 2014-15 Champions League last summer with Kansas City. Third stringer Maxime Crepeau has a shoulder injury, so German Kristian Nicht was brought in on loan from NASL team Indy Eleven to serve as backup.

A rousing win on away goals against Pachuca of Mexico in the quarter-finals has the Impact in a buoyant mood, even if they are coming off a 1-0 loss in their league opener last week at D.C. United.

Bush brings plenty of experience in knockout competitions.

"Any time you're in a cup scenario, it's either one game and you're out or the group stage and you're out, so every minute of every game means something," he said. "It helps every guy on the field to be more tuned in and focused on every play.

"It's a different approach than to league games. I enjoy it when it's one or two games and you're out. There's always something on the line."

The Impact beat Pachuca on counterattacks and will likely try to do the same against Alajuelense.

It will help that Montreal goes into the semifinals with confidence, even if the Costa Ricans crushed D.C. United 6-4 on aggregate in the quarter-finals.

"I don't know if we're necessarily underdogs right now," said Bush. "They beat D.C., which is a good team, but we're coming off a series in which we knocked off one of the best teams in the tournament."

The Impact will be without midfielder Justin Mapp, who dislocated and fractured his left elbow in D.C. and will be out for four months.

His spot on the right flank will likely go to speedy Dominic Oduro, with Jack McInerney as the lone forward. Rookie Cameron Porter, who scored the series winner against Pachuca, should be ready off the bench.

"Playing a big team in Mexico like Pachuca, you're definitely going to be the underdog," McInerney said. "I think teams disrespect and underestimate MLS teams and I think we've proved to be a solid team.

"But we can't overlook Alajuelense. They may not be as big as Pachuca, but they're a very good team."

The Impact are also without their 2014 player of the year Andres Romero, who has a quadriceps injury. Coach Frank Klopas expects him back for the team's MLS home opener March 28 against expansion club Orlando.

The Impact's game scheduled for April 4 in New York has been moved to Oct. 7 to give them a rest ahead of the semifinal second leg April 7 in Alajuela, Costa Rica.

The other semifinal has Herediano of Costa Rica against Mexican club America.