Mrazek, 23, will start over veteran goaltender Jimmy Howard, who started the majority of the Red Wings' games this season.
In 29 regular season games, Mrazek was 16-9-2 with a .918 save percentage and a 2.38 goals-against average. Howard was 23-13-11 with a .910 save percentage and a 2.44 goals-against average in 53 games this season.
After posting a .926 save percentage in December, Howard has not had a save percentage higher than .902 in each of the four months since. He missed time in January due to a groin injury.
Game 1 against the Lightning will be Mrazek's first playoff start of his career.
The first game of the series will be on Thursday at 7:30 p.m. ET. Detroit, the No. 6 seed in the Eastern Conference, was 43-25-14 this season, while Tampa Bay, the No. 3 seed, was 50-24-8.
- Molly Geary