As speculation grows that Joe Mauer will be back in the Twins lineup Tuesday against the White Sox, manager Ron Gardenhire said the four-time All-Star will be activated from the disabled list only when the team is convinced he has caught enough during his rehab from bilateral leg weakness.

After catching eight innings Wednesday, Mauer was back in the Class A Fort Myers lineup at catcher Thursday -- his first time catching on back-to-back days since early April. He finished 1-for-3 at the plate with a double and an RBI, and caught seven innings.

Mauer can return from the 60-day DL Sunday, and the Twins are off Monday. Gardenhire said he'd like to see Mauer catch at least three consecutive days, whether that's for Fort Myers or Class AAA Rochester.

"We saw that out of spring training, when we thought he was ready then," Gardenhire said. "We want to make sure we give him plenty of time here and plenty of ballgames to where it's not catch a game, sit out two."

Nishioka update Tsuyoshi Nishioka has been rehabbing his broken left fibula with Class A Fort Myers, but Gardenhire would like to see him play three or four games for Class AAA Rochester before returning from the DL.

"They talked about early next week for him [to return], too, but he hasn't played enough games and he's not going full out," Gardenhire said. "I would like to see him go to Triple-A and get him some ballgames and get him some little [better] competition, He's not been swinging great, so I want to see him go full out."

Span has concussion Denard Span was placed on the seven-day disabled list because of a concussion and outfielder Rene Tosoni was called up from Class AAA Rochester.

Major League Baseball adopted the new seven-day DL stint for concussion victims this year. The Twins determined that Span suffered a mild concussion, as well as whiplash, when he slid into Royals catcher Brayan Pena last Friday.

Span tried playing Monday in Cleveland and felt foggy. He will be eligible to return on Tuesday, but the Twins aren't sure how long he'll be out..

"I've just been instructed for the next couple days to take it easy and see what happens," Span said.

Etc. • Justin Morneau's MRI exam on his left wrist showed fluid but no structural damage. He was the DH Thursday.

• Jason Kubel (sprained left foot) is eligible to come off the DL Wednesday. He took swings in the batting cage, played catch, did some agility drills and said he felt OK.

• Joe Nathan (strained right flexor muscle) said he felt great throwing in the bullpen. He'll do it again Saturday, and if that goes well, he'll head out that day to begin a rehab assignment.

• Glen Perkins (strained oblique) also said he felt great throwing in the bullpen and is scheduled to pitch an inning for Class AAA Rochester on Saturday in Toledo, Ohio.

• Jim Thome (strained left quadriceps) also has pain in his hip, and the Twins have determined it all is being caused by his back. They plan to consult with doctors about giving Thome an epidural injection with the hope of getting him back to baseball activities. by the weekend.