Rantanen, who has 41 points (19 goals, 22 assists) in 42 games, crashed into the boards after being tripped by Lightning defenseman Erik Cernak at 7:18 of the second period. He appeared to be holding his left shoulder while leaving the ice. Cernak received a minor penalty.
Rantanen was out 16 games from Oct. 25-Nov. 29 with an ankle injury.
The Avalanche, who are 0-2-1 in their past three games, were already without goalie Philipp Grubauer, center Nazem Kadri and forwards Matt Calvert and Colin Wilson; each has a lower-body injury.
"I think every team's going through it a little bit," Colorado coach Jared Bednar said. "But you start racking them up with Grubauer, Kadri, Calvert, now Mikko, our other guys got to step up. It's a great opportunity.
"We have to find a way to carve out wins like we did early in the year. It's going to get tougher and tougher, but hopefully we can get those guys healthy and back to join our team as soon as possible and guys are going to get opportunities and callups, and it's] more ice time for guys that have been here wanting more ice time. We'll see what they got."
Grubauer
[was injured against the Los Angeles Kings
on Saturday at Falcon Stadium in the 2020 Navy Federal Credit Union NHL Stadium Series. Bednar said he was still being evaluated.
Calvert also was injured Saturday and will be out weeks, according to Bednar. Calvert has 25 points (12 goals, 13 assists) in 50 games.
Kadri was injured Feb. 9 against the Minnesota Wild and has been out the past four games. He has 36 points (19 goals, 17 assists) in 51 games.
Wilson hasn't played since Oct. 26 against the Anaheim Ducks. He had surgery and is out indefinitely.
Kadri and Wilson are on injured reserve.
