When Joe Mauer emerges from the players-only section of the Twins clubhouse at Target Field, his stall is the first one on the right, while Justin Morneau's had been the first one on the left. The two had not been far from each other since becoming established major leaguers. Their stalls were next to each other during spring training and were separated by one empty stall at the Metrodome.

On Thursday, Mauer looked over to where his sidekick used to sit and saw a cleaned-out stall with a few T-shirts hanging. Now the multi-time All-Stars, former MVPs and close friends have been broken up by Morneau's trade to Pittsburgh.

Mauer, who hasn't played since suffering a concussion Aug. 19, thought they would be teammates forever.

"That was the hope," said Mauer, speaking for the first time since Morneau was traded to the Pirates for outfielder Alex Presley and a player to be named later. "One thing why we became such good friends is that we had the same goals, especially professionally. We might have been a little different when we first met. But he's the guy who works hard, plays the game the right way, always wants to get better."

Mauer was working out Saturday when, during a break, he checked his phone and saw a message from Morneau. One day after winning the game with a home run in Texas, Morneau was headed to Pittsburgh and the NL Central pennant race.

Mauer was happy that his buddy has a shot at the postseason — but he was steamed.

"At first when I heard about it, there was a lot of frustration and things like that, on a personal level," Mauer said. "Probably a little selfish for me. I enjoyed Justin as a teammate for 10 years, and I've known him for 12. We go back a long way, but the more and more I think about it, it is a good move for him professionally.

"He's meant a lot to this team over the years and is a big reason for our success. And just not our team, in the community, too. He's going to be missed on a whole lot of levels."

Mauer, when announcing his eight-year, $184 million deal in 2010, said he was confident the club was committed to winning. But the Twins are about to lose 90-plus games for the third season in a row, while most of the links to their success from 2002-2010 are playing elsewhere. Mauer, Glen Perkins and Brian Duensing are the only remaining members of the 2010 team, the last one to make the postseason.

"It's been frustrating, you can definitely say that," Mauer said. "[Morneau] is one of the last ones. We have had a lot of turnover the last few years. Turnover happens, I guess."

Mauer slowly is working his way back from that concussion he suffered when he took a foul ball off the facemask. He's improving, and is able to swing a bat, run and lift weights.

He's able to exert himself more and more, but symptoms continue to return, forcing him to throttle back.

"This process has been a little longer than I hoped," Mauer said.

His goal is to return to the lineup — and to catching — before the season is over.

There has been plenty of speculation about Mauer needing to change positions to remain on the field. Mauer had a two-part answer to that possibility.

Part one: The specialists he's seen at the Mayo Clinic in Rochester haven't told him he shouldn't catch.

"I went down to Mayo and talked to all those guys," Mauer said. "And they said, 'You've got to let it heal,' and when it heals, they have 100 percent confidence that I can go back to catching, so I'm not too worried about that."

Part two: He still expects to discuss with the Twins during the offseason how much catching he'll do in the future.

"I still believe that being behind the plate helps our team win," he said. "It's what I know, it's what I love. But it is something I need to talk to them about and see what's the best way to help this club win.

"I still believe that me catching is the best way, but we have to see what happens this offseason and how the team shapes up."