Nishioka, who suffered a broken left fibula on April 7, is expected to play five innings at shortstop on Saturday in extended spring training.
"They did another X-ray and everything looked great, so he got the OK to go," Twins trainer Dave Pruemer said. "He's fired up and has been doing a lot of drills at shortstop."
The Twins say they'd like him to get at least 50 at-bats in the minors.
Mauer is already playing at extended spring training. He served as the team's designated hitter on Friday.
Left-hander Jose Mijares is scheduled to pitch at Class A Fort Myers on Friday and Saturday.For more baseball news, rumors and analysis, follow @cbssportsmlb on Twitter or subscribe to the RSS feed.