Grubauer did not play in a 4-3 win against the St. Louis Blues. Devan Dubnyk made 31 saves in his Colorado debut after he was acquired in a trade with the San Jose Sharks on Saturday.
"It'll be at least 14 days before his next game," Colorado coach Jared Bednar said of Grubauer. "Not ideal, but I know he'll be hungry to get back in the net when he's healthy."
Grubauer would miss at least seven additional games if he is out through April 28. Colorado has 13 games remaining.
Grubauer is 25-8-1 with a 2.00 goals-against average, .920 save percentage and five shutouts in 34 games (33 starts) this season. He was tied for the most wins in the NHL with Andrei Vasilevskiy of the Tampa Bay Lightning and tied for most shutouts with Marc-Andre Fleury of the Vegas Golden Knights.
Grubauer made 35 saves in a 4-2 win against the Arizona Coyotes on Monday.
"It was a scheduled start for 'Grubi,'" Bednar said. "We had gotten him some rest on the road and, you know, he played last game and we were getting ready to go with him again today."
With Pavel Francouz having not played this season because of a lower-body injury, Colorado traded for Dubnyk after already acquiring Jonas Johansson from the Buffalo Sabres on March 20.
Dubnyk was 3-9-2 with a 3.18 GAA, .898 save percentage and one shutout in 17 games (13 starts) with San Jose this season.
Johansson is 3-0-1 with a 1.87 GAA and .929 save percentage in five games (four starts) with Colorado, including his first NHL shutout in a 2-0 win at the Anaheim Ducks on Friday.
Last season, Grubauer and Francouz were injured in the Stanley Cup Playoffs. Michael Hutchinson, their third-string goalie, started the final three games of a seven-game loss to the Dallas Stars in the Western Conference Second Round.
"We saw last year how important goalie depth is in the playoffs, actually over the last few years," Bednar said. "And to be able to acquire the two guys we've acquired here recently I think it just makes our team deeper and stronger."
Colorado (30-9-4) is first in the Honda West Division, four points ahead of the Vegas Golden Knights. The top four teams will qualify for the playoffs.
