Jake Muzzin is expected to be out four weeks for the Toronto Maple Leafs because of a broken left hand.
The defenseman was injured blocking a shot by Tampa Bay Lightning defenseman Victor Hedman in the second period of a 4-3 win Tuesday.
Muzzin has 23 points (six goals, 17 assists) in 53 games this season. He signed a four-year, $22.5 million contract (average annual value $5.625 million) with Toronto on Monday,
"He's been playing great, no question it's a big loss," captain John Tavares said Tuesday. "But we can't hang our heads and think, 'Why us?' As a group we have to step up and fill that void. When [rookie defensemen Rasmus Sandin and Timothy Liljegren] get more opportunity, that's their chance."
The Maple Leafs recalled defenseman Calle Rosen from Toronto of the American Hockey League on Wednesday.
Toronto was already without top-four defensemen Morgan Rielly (foot, 18 games missed) and Cody Ceci (ankle, 10 games missed). Coach Sheldon Keefe said Wednesday each is week to week.
"It's tough having [them] all out at the same time, but it's also an opportunity for a lot of us young guys," defenseman Travis Dermott said. "We all embrace it."
Injuries have forced inexperienced defensemen into the spotlight for the Maple Leafs. Justin Holl (75 games), Sandin (24), Rosen (16) and Liljegren (eight) have 123 games of NHL experience; Muzzin (579 games), Rielly (516) and Ceci (494) have 1,589.
"That's why you have depth in an organization," Keefe said. "We have guys that can step in. They are not AHL-caliber players anymore. They're NHLers, and we have confidence in them."
The Maple Leafs (33-23-8), who play at the Florida Panthers on Thursday (7 p.m. ET; TVAS, FS-F, TSN4, NHL.TV), are third in the Atlantic Division, two points ahead of the Panthers.
NHL.com staff writer Mike Zeisberger contributed to this report