Updated

Minnesota Twins star Joe Mauer is injured — and sick.

Minnesota manager Ron Gardenhire said before Friday night's game against Tampa Bay that Mauer has a viral infection, which the team believes increased the catcher's body soreness recently.

"It tells us that there's probably a reason why he's been so sore, and that's his system is fighting a viral infection," Gardenhire said. "It kind of helps us in probably knowing a little bit better where we stand and what's really going on."

Mauer was placed on the 15-day disabled list Thursday because of leg weakness stemming from offseason arthroscopic surgery on his left knee. Gardenhire hopes Mauer will be able to return in a couple weeks.

"I think it eases everybody's mind knowing he's got a viral infection, flu-bug thing, and we all know how you feel when you get that stuff," Gardenhire said. "Probably got him feeling worse than he probably really is."

Twins General manager Bill Smith said Mauer went to a hospital for evaluation and treatment Thursday night after "suffering from extreme flulike symptoms."

"He's been feeling pretty good until this last weekend," Gardenhire said. "A little concerned (Thursday) as everybody and Joe was, too. He wants to get out there and play. It's hard to do when you're aching all over the place. This is a step in the right direction."

Smith said Mauer was sick during and after the 4-3, 10-inning loss to the Rays. Mauer received fluids and antibiotics and was discharged back to the team's hotel.

The three-time AL batting champion and 2009 AL MVP is scheduled for a follow-up visit to a specialist in Baltimore. The doctor treated a lower-back problem that put Mauer on the DL for a month in 2009.

Mauer is expected to start a rehab program next week in Minnesota.