MONTREAL — The Major League Soccer season hasn't even started and already the Montreal Impact's lack of depth has been exposed.

Injuries have left the Impact with one healthy forward, Matteo Mancosu, and one centre back, Victor Cabrera, heading into their regular season opener Sunday in Vancouver.

The club that could not afford any injuries to key players was dealt a massive blow when one of their top off-season signings, French central defender Zakaria Diallo, went down during training on Tuesday. The club has yet to confirm reports that Diallo suffered a ruptured Achilles tendon, but players acknowledge that he will be gone for months and possibly the entire season.

"It's difficult for us and for him," star midfielder Ignacio Piatti said Thursday. "His injury is for a long time, so now the coach has to decide who plays in the back.

"For us, it doesn't change things. We still need to play a good match."

Piatti expects new coach Remi Garde to stick with a four-man back line, a formation they have used through the pre-season. Candidates for Diallo's spot include left back Jukka Raitala and holding midfielder Marco Donadel.

"No one knows yet who's going to play but if the coach needs me at any position I'm available," said Raitala, who was acquired along with fullback/midfielder Raheem Edwards in a deal that sent the former anchor of the central defence, Laurent Ciman, to expansion Los Angeles FC.

Among back-up centre backs from last season, Wandrille Lefevre was cut before camp and Hassoun Camara retired.

And despite the depth issues, the club loaned 20-year-old central defender Thomas Meilleur-Giguere as well as forward Michael Salazar to the Ottawa Fury of the USL on Wednesday.

The Impact are hoping Garde's tighter new defensive system will help cut down goals-against no matter who plays, but they will surely miss 31-year-old Diallo's experience and his six-foot-three frame. The defence may be severely tested by the high-ball abilities of Vancouver's new striker Kei Kamara, a long-time Impact-killer.

"Of course it's disappointing for all of us, but unfortunately it's part of the game and these sorts of things happen sometimes," said Raitala, who has played only a few games at centre back, none in MLS. "But we have a good team, a strong roster and we're ready."

Piatti, the left-side midfielder who led the team with 17 goals in each of the last two seasons, is hoping the Impact can repeat what they did on March 6, 2016 when they opened the season with a 3-2 win in Vancouver.

"We feel bad for (Diallo), he's a great player and a good person and then this happens a few days before the start of the season," said Piatti. "That's not good.

"But mentally and physically we're good. We're ready to start the season. We hope to get a result there and get off to a good start."

It is a similar scenario up front. Anthony Jackson-Hamel, a nine-goal scorer as a rookie last season, tore a hamstring in the pre-season and will be out at least a few weeks. Veteran Dominic Oduro is still with the team, but perhaps only because he has a year left on his contract and the Impact couldn't trade his $330,000 salary. Garde doesn't use him.

That leaves Mancosu, who slumped to only three goals in an injury-marred 2017 campaign after some stellar play when he joined the squad midway through the previous season.

"I'm very happy because I feel better physically and I can play my soccer," the 33-year-old said.

At the end of his scrum with the media, Mancosu asked to make a statement in which he expressed support for Diallo, who he said suffered a "bad injury," and wished him a speedy recovery. It was another indication that the former Stade Brestois defender's condition is serious, even if the team has yet to provide details. That may come when Garde speaks on Friday.