The Twins are down a starting pitcher with Michael Pineda going on the 10-day injured list with right knee tendinitis.
Taking Pineda's spot on the roster is left-handed pitcher Devin Smeltzer, who'll make his major league debut when he gets into a game.
The Twins and Brewers close out their two-game interleague series Tuesday nght at Target Field.
Martín Pérez starts for the Twins against Milwaukee's Zach Davies.
Pineda has started 11 games this season for the Twins, including Monday night against Milwaukee, and is 4-3 with a 5.34 earned run average.
He did not figure in the decision in the 5-4 loss to the Brewers.
Pineda signed with the Twins as a free agent in the winter of 2017 after undergoing Tommy John surgery on his right elbow.
He played in parts of four seasons with the New York Yankees.
Smeltzer, 23, came to the Twins from the Los Angeles Dodgers last summer in a straight-up trade that sent Brian Dozier to the west coast.
He's a former fifth round draft choice who made four starts this season at Triple-A Rochester after getting promoted from Double-A Pensacola.
Smeltzer's combined record this season is 3-2 with a 1.15 ERA, and was the Twins' minor league pitcher of the week earlier this year.
Smeltzer will wear uniform number 31.
The Twins 40-man roster is now at 40.