Despite a thrilling comeback OT win against the rival Boston Bruins on Tuesday, the Toronto Maple Leafs suffered a major loss when Chris Tanev left the game only minutes in after taking a rough hit from Bruins forward John Beecher. He slowly made his way to the bench, and then headed to the dressing room.

Tanev did not return, being officially ruled out prior to the second period due to an upper-body injury. While head coach Craig Berube said post-game that he would need to be evaluated and didn’t expand further, Sportnet’s Luke Fox noted that Tanev left TD Garden with his right arm in a sling.

Speaking after Tuesday’s contest, Leafs alternate captain Morgan Rielly spoke on Tanev and his importance to the team’s blue line, per The Athletic’s Joshua Kloke.

“Tanev is one of the best defencemen in the league in my opinion,” said the 30-year-old defenceman. “He plays big minutes, he plays hard minutes against the other team’s best players. I thought the (defence) played well and I thought the forwards helped us out. Obviously, we hope he’s not out too long.”

Overtime hero Mitch Marner added on his praise when asked what Tanev brings to Toronto’s roster.

“Everything,” he said. “He plays against the best players every single night. He starts in the defensive zone a lot of times and doesn’t care, doesn’t complain about it, just does his job. And he’s a guy that you love to have on your team and in the locker room.”

The comments from these two key Leafs highlight the gap that Tanev will be leaving on the team’s blue line. And depending how long his absence will be, it may have a major effect on how the Leafs shores up their roster ahead of the upcoming trade deadline.

With a typical focus on offensive talent, it’s been long said that Toronto still needs to do more to strengthen their defensive depth. However, with some stellar performances in net this season from their goaltending duo, that conversation has quieted down a bit. Now in the absence of Tanev, it may need re-visiting. With just over a week until the March 7 deadline, the Leafs will be anxiously awaiting the medical evaluation of Tanev to see if they need to do some last minute shopping to fill his crucial role on this roster.