Sandin was injured early in the second period. He was on the ice for Toronto's second goal of the game.
It's rare these days for a Toronto Maple Leafs game to pass without an injury to a defenseman.
Thursday against the Tampa Bay Lightning was no exception.
The club announced that Rasmus Sandin has a neck injury and would not return.
It's not immediately clear what took place that caused the Swedish defenseman's injury.
"He'll have to get evaluated today and again tomorrow t get a better idea of what's happening with him," Maple Leafs head coach Sheldon Keefe said following the team's 4-1 win against Tampa.
Keefe added there was a specific incident that caused Sandin's injury although it was "innocent".
"At this point I'd say it's more precautionary more than anything," Keefe said. "We're going to need some time for things to settle to know exactly what is happening and what his status might be."
He was last on the ice in the opening minute of the second period when Auston Matthews scored a goal that made it 2-0 Toronto.
The Maple Leafs have seen many different injuries to their defense corps this season. They are currently without Morgan Rielly (knee) and Jake Muzzin (cervical neck issue) Victor Mete (lower-body) and Carl Dahlstrom (shoulder). They've been without TJ Brodie (oblique) and Timothy Liljegren (hernia) for other stretches of the season as well.
Liljegren left Thursday's game against the New York Rangers with a hand injury but was able to return for the following game against the Washington Capitals.
Sandin had two goals and 13 points in 32 games heading into Tuesday's contest.