The Twins, who clinched the American League Central Division title nearly a week ago, were in Kansas City Tuesday for the second contest in a three-game series. The Royals took the opener Monday 10-8.
"Mauer swung ... and ran around," Gardenhire said in a report on the Twins' Web site. "He feels a lot better. I don't know if he's going to play here [in Kansas City] or not. He might want to DH [Tuesday] or the next day."
There were "no guarantees" that Mauer would get into the Royals series, Gardenhire said.
Mauer suffered a knee injury while swinging Sept. 19 in a game against Oakland. An MRI exam showed no serious damage to the knee.
The 27-year-old Mauer, the only catcher in major league history to win three batting titles, was batting .331 when he was injured. In games through Monday he was second to Josh Hamilton of Texas, who led the American League with a .361 average.
Mauer was the league's MVP in 2009.