Montreal hosts fellow Major League Soccer club San Jose at Saputo Stadium in the opening game of Group 5 competition. The Earthquakes qualified as last season's MLS Supporters Shield winners. They are in eighth place in the Western Conference with 30 points and have won three in a row in league play to move within three points of a playoff spot.
Impact goalkeeper Evan Bush will get the start against San Jose, one of four American MLS sides to qualify for the tournament.
"We know what they bring to the table and the players they have and it's a quality side and they're in the Champions League for a reason," said Bush, who has backed up Troy Perkins in league play but started each of Montreal's four games in the Amway Canadian Championship. "They're starting to turn a corner in league play as well so it's a team that we're going to have be up for."
The Impact beat Vancouver in the ACC final to win their eighth Voyageurs Cup and qualify for their second CONCACAF Champions League tournament, their first in five years.
Montreal assistant coach Mauro Biello played for the Impact during their inaugural trip to the competition. Four years before the team became an MLS expansion franchise they won their group stage before losing to Mexico's Santos Laguna in the 2008 quarter-finals.
"It's a huge honour especially after winning the Canadian championship," Biello said. "Being part of a Champions League is always something not only for the players but also for the city, to be part of an international tournament now where you have the possibility of going far and doing well and being something on not only locally but on the international level.
"I remember the last time in 2008 when we had 56,000 people against Santos Laguna you know it wasn't only in North America that they were talking about us, so it's something very big and very special and a lot of players want to do well in this tournament."
After streaking to first place in the East behind a 9-2-3 start, Montreal has struggled in league play with only one win in its last seven MLS outings.
The Impact followed up that 1-0 victory at home over Kansas City on July 27 with a discouraging 3-1 loss in Washington on Saturday.
"We don't have too much time now to think about what happened on Saturday because there's a big game obviously on Wednesday night," Montreal captain Davy Arnaud said. "It's a different competition. It's now a little bit of a different challenge for us but we have to approach the game the same way like we do every home game and it's going to be important to start off things the right way on Wednesday."
Justin Mapp scored a pair for the Impact in a 2-2 draw in San Jose on May 4. Montreal beat the Earthquakes 3-1 in their only previous meeting at Saputo Stadium on Aug. 18, 2012.
"You only play a certain number of group games so every game is super important," Arnaud said. "They're going to come in here and they know that they need to get some kind of result if they want to advance, just as it's going to be the same for us when we go on the road. It's going to be a tough game. They're a good team, they got a good result this past weekend so they'll be confident and I think you saw last year when they came here the kind of game it was, I think we can expect more of the same."
Earthquakes striker Chris Wondolowski has won the MLS Golden Boot two of the last three seasons, including last year when he scored a staggering 27 goals in 32 games. He leads San Jose with seven goals.
"They have just a lot of battlers up top and then a clinical finisher in Wondolowski, so you're dealing with crosses and then picking up the second balls," Bush said. "They thrive on balls that are knocked down where they can battle and win that second ball and then find chances on goal.
"So it's going to have to be a game where we're going to have to be tuned in mentally and physically and it's not necessarily something that tactically you prepare for a whole lot differently but it's the mentality of going into the game and trying to win those balls."
There could be a few fresh looks to the Impact lineup. Argentinian midfielder Hernan Bernardello signed as the Impact's second Designated Player on July 23 and travelled with the team to Washington, though he did not play.
Bernardello and fellow newcomer Adrian Lopez, a Spanish defender who signed on July 26, give coach Marco Schallibaum options as Montreal plays midweek with a big game looming in Chicago on Saturday night.
Blake Smith, the Impact's top pick in the 2013 MLS SuperDraft, scored the winning goal in stoppage time against Kansas City. He came on as a substitute and has yet to start for Montreal.
"When you play in these tournaments during the league you're going to have to use a lot of your lineup and a lot of players will be getting some time to play and some minutes and some experience at the same time," Biello said. "So it's also a process where the team could grow from this and learn and gain experience, and not only for players that play regularly but for players that don't have as much time, to come in and also show to the coach that they could be also an option in a regular season game."
The Impact travel to Guatemala to play C.D. Heredia on Aug. 21. Montreal plays its second leg against the MLS Earthquakes in San Jose on Sept. 17 before hosting Heredia one week later to close out the group stage.
"It's nice to be at home the first game because if you come in home and you have a good game and you get the win it starts you out with a positive feeling so you don't feel like you're kind of playing catch up if you don't win that first game," Arnaud said. "So in that sense it's good. And also we have that last game at home as well which I think in terms of the scheduling, the way it worked out, it's worked out well for us. We have to take advantage of that now."