Walters will look to continue the progress he began to show his last time out, when he held Cleveland to two earned runs over five innings. Walters had lost his first two starts since returning from the disabled list while allowing 12 runs in only nine innings.
Smyly was kept as a backup option in the event that Max Scherzer couldn't pitch the opener, but Scherzer did. The lefty Smyly hasn't started since limiting the Angels to one earned run on four hits over six innings on Aug. 25. He has struggled in relief work since then, posting a 9.82 ERA in 3 2/3 innings over four appearances.
Twins: Span playing well since return
Denard Span is hitting .316 with two three-hit games in nine contests since returning from the disabled list earlier this month. A sprained sternoclavicular joint sidelined him for nearly a month.
"He's your prototypical leadoff guy," manager Ron Gardenhire said. "He knows what he's doing up there."
Sunday's doubleheader leaves a gap in Minnesota's rotation for the team's game against the Yankees on Wednesday. Gardenhire said relievers Anthony Swarzak and Brian Duensing are both viable options.
Both have struggled as starters this season. Swarzak is 0-4 with an 8.35 ERA in four starts while Duensing is 2-8 with a 6.92 mark in 11 outings.
Tigers: Prince seeing lefties at same rate
Prince Fielder is still seeing matchups against left-handed pitchers in September at about the same frequency he did in August. This goes against conventional wisdom, which would presume that Fielder would face more left-handers than normal because of expanded September rosters.
Fielder registered nine hits, six walks, and five strikeouts in 39 at-bats against left-handers in August. He is 9-for-40 against southpaws this month.
Miguel Cabrera is two doubles away from 40 on the season, which would join him with Hank Greenberg as the only Tigers to hit 40-or-more doubles and 40-or-more home runs in the same season. Greenberg did it in 1937 and '40.
Cabrera is also hitting .378 (17-for-45) with runners in scoring position dating to Aug. 1.
Josh Willingham entered Saturday's game on pace for 118 RBIs this season, which would be the ninth-highest total in Twins history. It would also be the most by a Minnesota player since Justin Morneau drove in 129 runs in 2008.
Minnesota's pitchers have amassed a 5.84 ERA (74 earned runs over 114 innings) in 13 games against Detroit this year.
Detroit has won 26 of its last 35 games against to Minnesota dating to Sept. 2, 2010.
Saturday marked the 11th time the Twins have been shut out this season.