The veteran defenseman was injured midway through the third period of Game 1 Sunday and was seen by media inside Toronto's Scotiabank Arena heading down the tunnel to the locker room. He did not return in the Bolts' 3-2 loss.
Whether McDonagh will be available for the remainder of the Second Round series against the Bruins is unknown.
Cooper wouldn't divulge who would enter the lineup to replace McDonagh or how the Lightning will rearrange defensively to compensate for his absence.
"Next man up," is all the Bolts bench boss would offer.
McDonagh is a key member of the Lightning's defensive corps and his inability to play will be a considerable blow for the Bolts in a pivotal game in the series. McDonagh paces Tampa Bay for average time on ice at over 26 minutes per game and ranks first in the NHL among players still competing in the 2020 Playoffs. He's part of the Lightning's shutdown pair along with right-shot defenseman Erik Cernak, often drawing the assignment of stopping the opposition's top line - in Boston's case, the David Pastrnak-Patrice Bergeron-Brad Marchand trio - or stepping over the boards for defensive zone face-offs. He's also the Bolts' top penalty killer averaging 3:40 of shorthanded time on ice this postseason.
McDonagh has tallied three assists during the 2020 Playoffs.
"It's going to be difficult I think with how he's played for us, how good he is on the PK," Lightning forward Alex Killorn said about McDonagh's absence for Game 2. "He's a great defensive player for us, but I think next-man up-mentality. When you look at the guys that have been waiting to play, great defensemen, and they've been practicing hard every day. If anything, they'll have their legs."
The Lightning have options to replace McDonagh. Braydon Coburn could get his first start this postseason. Like McDonagh, Coburn's a left-shot defenseman, and his 134 career playoff appearances are the most of any player on the Lightning roster. Or the Bolts could turn to Luke Schenn, who warmed up prior to the opening game of Tampa Bay's First Round series against Columbus when Victor Hedman was a game-time decision but ultimately did not play.
