Duensing has posted a 1.08 ERA in six appearances dating back to Sept. 2, with four strikeouts and two walks in 8 1/3 innings.
He was especially effective against the White Sox on Saturday, when he threw 3 1/3 scoreless innings and retired the first 10 batters he faced.
"He did a really nice job," Gardenhire said. "Came in, threw the ball over the plate, used all of his pitches, looked really confident and relaxed out there, and got us a few really good innings when we desperately needed them after another starter going four innings."
Duensing has split time between being a starter and a reliever this season, but has fared better out of the bullpen. He has a 2.77 ERA in 48 2/3 innings as a reliever, compared to a 6.92 ERA in 52 innings as a starter.