The team announced Thursday that the ace would undergo Tommy John surgery on his left elbow.
Injuries have been a problem in recent seasons for the 30-year-old after showcasing impressive durability early in his career.
Sale averaged 205 innings pitched from 2012 to 2017, leading the majors with 214.1 frames in 2017. He couldn't continue this trend in 2018 as shoulder problems limited him to 158 innings. Elbow issues then caused his 2019 campaign to end in mid-August.
While he had high expectations to begin 2020, a flexor strain shut him down early in spring training. He went 6-11 with a career-worst 4.40 ERA in 2019 and will make $30 million this season while sidelined.
The latest injury will further challenge Boston's lack of rotation depth behind Eduardo Rodriguez and Nathan Eovaldi. And given that the team already traded Mookie Betts and David Price this offseason, it's another blow for the team's postseason hopes.