BOSTON — Boston Bruins left winger Brad Marchand suffered a concussion during Saturday’s 4-2 loss to the Montreal Canadiens and is out indefinitely, according to the team’s website.

“Yeah, March suffered a concussion,” Coach Claude Julien was quoted on the website. “We’re going about it with the League’s protocol with concussions, and his return will be dictated by how quickly he recovers … so we have no timetable for him.”

The gritty forward seemed to be on the receiving end of an inadvertent elbow from Montreal’s Dale Weise late in the third period. An unsteady Marchand skated to the bench and had to be assisted down the tunnel to the dressing room.

With Marchand sidelined for Monday’s home game against the Tampa Bay Lightning, Brett Connolly is likely to take his place on a line with center Patrice Bergeron and right winger Loui Eriksson.

Marchand had no points in Boston’s first two games, both losses.

CANADIENS 3, SENATORS 1: Tomas Plekanec scored twice in the first period and Mike Condon had to make just 19 saves in his NHL debut to help Montreal beat host Ottawa.

Condon, 25, allowed only a short-handed goal by Jean-Gabriel Pageau midway through the second period. Torrey Mitchell added a goal for Montreal in the third period.

Montreal improved to 3-0-0, while Ottawa dropped to 2-1-0.

Matt O’Connor made 31 saves for Ottawa in his NHL debut.

Plekanec opened the scoring at 9:41 of the first period. Plekanec got his third the season with 1:26 left, breaking in alone to beat O’Connor through the legs.

Pageau pulled Ottawa within one on a two-on-one break with Curtis Lazar.

Mitchell redirected P.K. Subban’s shot from just inside the blue line at 5:41 of the third.

Condon and O’Connor are the first goalies to make their first NHL starts in the same game since Oct. 14, 1967.