The goalie aggravated the injury in a 4-1 loss to the Dallas Stars on Tuesday, when he made 34 saves and played the entire game.
Avalanche coach Jared Bednar said Grubauer, who is 6-3-2 with a 2.80 goals-against average and .915 save percentage in 11 starts this season, would not be available against the Nashville Predators on Thursday (9 p.m .ET; ALT, FS-TN, NHL.TV) or the Columbus Blue Jackets on Saturday.
He could return for their five-game road trip that begins against the Winnipeg Jets on Tuesday.
"He tweaked it last game against Dallas, but something's been bugging him for a little bit," Bednar said.
Pavel Francouz (2-2-0, 2.73 GAA, .919 save percentage) will start against the Predators. Adam Werner, who was recalled from Colorado of the American Hockey League, will be the backup.
Colorado, which is 0-4-1 in its past five games, was already without top-line forwards Mikko Rantanen (week to week) and Gabriel Landeskog (out indefinitely). Each has a lower-body injury.
