Backup Pavel Francouz started in Kuemper's place, recording 24 saves to help the Avalanche take a 2-0 lead in the best-of-seven series.
Kuemper exited Game 1 in the second period and was replaced by Francouz. Coach Jared Bednar has declined to provide further details on Kuemper, including how long he expects the netminder to be out.
The veteran carried Colorado in the crease all regular season, going 37-12-4 with a .921 save percentage. Francouz complemented him most of the way with equally strong stats (15-5-1, .916 SV%).
This is the second injury Kuemper has suffered in the playoffs. He left in Game 3 of Colorado's first-round sweep of Nashville after Predators forward Ryan Johansen struck him in the eye with a stick. Francouz finished out that series, posting a .902 save percentage and 2.97 goals-against average.
Kuemper returned to face the St. Louis Blues in the second round and has amassed a solid playoff record at 6-2-0 with a .904 SV% and 2.44 GAA. He made 13 saves on 16 shots prior to leaving Game 1.
While it's unclear how long Kuemper will be unavailable, Bednar said he isn't worried about Francouz taking over.
"We have a lot of confidence in him," Bednar said of Francouz after Thursday's morning skate. "He's played really well for us over the last few years. Stepping into the situation in the Nashville series, he did a great job for us. He came in the other night and did a nice job for us. We're completely confident he can get the job done."