ST. PETERSBURG, FLA. - Twins catcher Joe Mauer has bilateral leg weakness and will fly to Baltimore on Friday to see a specialist, another blow -- a big one -- to a club that was already reeling after a 4-3 loss in 10 innings to Tampa Bay on Thursday.

He has been placed on the 15-day disabled list and will be replaced by catcher Steve Holm, who has been called up from Class AAA Rochester. The Twins hope that Mauer, after seeing the specialist, will go on a rehabilitation program that will get his legs strong, eliminate the soreness he is having elsewhere because of it and return to action.

Twins manager Ron Gardenhire said the weakness in Mauer's legs "is causing all kind of soreness in his hips, and he's compensating because of the [left knee] surgery he had this winter and he's starting to get sore in other places. So we are just going to shut him down.

"He is definitely very, very sore over the last few days -- his shoulder, his elbow -- and we think it's his legs just not strong enough underneath him and he says he feels terrible.

"His knee is actually feeling OK but he's compensating for the weakness in his upper leg, this is what I was told, that's causing a lot of other problems."

Mauer will see the same specialist who treated his inflamed right sacroiliac joint in 2009 that caused him to miss the first month of the season. After going to Johns Hopkins to see the specialist, Mauer returned after a month to win the AL batting title and Most Valuable Player Award.

His trip to Baltimore is somewhat up in the air because Mauer caught the flu Thursday. He was laid out in the trainer's room after the game and unable to speak with reporters. "Mauer has been severely under the weather for the last several hours," General Manager Bill Smith said.

Mauer played Sunday against Oakland at Target Field. After the off-day Monday, Mauer was expected to play Tuesday night and Wednesday afternoon against Kansas City. But he couldn't go Wednesday, needing a day off.

"Then he came to me and said he's sore," Gardenhire said. "I thought, 'Well, we have to see where we are at here because we just had a day off.' "

On Thursday afternoon, Gardenhire had a lengthy meeting with Smith and head trainer Rick McWane before the game to go over plans for Mauer.

Once again, the immensely talented Mauer is facing an injury issue. He had knee surgery in December and appeared in just eight spring training games while he got his legs into shape. He took three injections of Supartz, a synthetic lubricant, to help get him through the season. And Mauer frequently spoke during camp of getting his legs ready for the season.

It's crushing for the slow-starting Twins, who enter Friday 4-8 and have not played up to their capabilities. Second baseman Tsuyoshi Nishioka is out for about a month because of a broken left fibula. Now their No. 2 and 3 hitters are out of the lineup.

While the Twins can plug in Luke Hughes and Michael Cuddyer at second, there is no way they can plug in someone for Mauer.

Drew Butera, who is very strong defensively and a good game-caller behind the plate, is not a threat with the bat. Holm, 31, has 53 games of major league experience.

Righthander Carl Pavano -- who pitched eight scoreless innings Thursday before the Rays rallied off Joe Nathan and Matt Capps -- has spoken to Mauer about putting pressure on himself to stay in the lineup because of the responsibility that comes with having an eight-year, $184 million contract. He doesn't want Mauer to blame himself about not being in the lineup and get healthy so he can perform up to his abilities.

"He needs to forget about that contract and be just himself," Pavano said. "I love that guy to death, and I just want him to be able to play."