Lewis felt soreness in his knee during spring intake, and an MRI revealed the tear.
It could be 9-to-12 months before he returns to full play, according to Twins president of baseball operations Derek Falvey.
The 21-year-old slashed .236/.290/.371 with 12 home runs and 49 RBIs across multiple minor-league levels in 2019. He also hit .353/.411/.565 with 20 RBIs over 22 Arizona Fall League contests that same season.
The Twins drafted Lewis with the first overall pick in 2017. He's the No. 17-ranked prospect in baseball, according to MLB Pipeline.