MINNEAPOLIS -- Joe Mauer is back in the lineup for the Minnesota Twins after missing six games for the birth of his twin girls. Slugger Josh Willingham may not be all that far behind him.

Mauer was hitting third and playing catcher in the series opener against Kansas City on Tuesday night. Mauer left the team on the West Coast to rush home to be with wife Maddie, who gave birth to twins Maren and Emily. Both were born a few weeks premature and weighed under 5 pounds. They remained in a nearby hospital as a precaution, but Mauer said both are happy and healthy.

"It's pretty neat just to stare at them. I probably stared at them for hours when I was there at the hospital," he told reporters after a ceremony to unveil the new logo for the 2014 All-Star game, which will be held at Target Field next summer.

They are the first children for Mauer, who had to charter a plane home from Los Angeles last Tuesday night and rush to the hospital when he got the call that the kids were coming a little early. The girls were born early Wednesday morning, shortly after Mauer arrived at the hospital.

Willingham has been on the disabled list since July 2 after having surgery to repair a torn meniscus in his left knee. He took some swings in early batting practice on Tuesday and hopes to begin a rehab assignment by this weekend or the start of next week.

"My knee feels good," said Willingham, who is wearing a brace to try to ease the strain on the joint. "A lot better than it did before I had surgery. It was obviously bothering me for a pretty good while."

Coming off a career year in 2012, Willingham tried to play through knee pain for much of the first half of the season, and it cost him. He is hitting just .224 with 10 homers and 37 RBIs, a far cry from the powerful force he was for the Twins last year.

The quick healing time has Willingham encouraged that he made the right decision to get the surgery during the season rather than try to play through the pain for the rest of the year.

Willingham will take more batting practice the rest of the week and ramp up his activity heading into a rehab assignment. He was hopeful that his time in the minors would be short and he could rejoin the Twins as early as a weekend series in Chicago against the White Sox from Aug. 9-11. But manager Ron Gardenhire said he thought that timeline might be a little optimistic, and the Twins will wait to see how his knee responds to running the bases and playing in live game action in the minor leagues before making any decision.

"I'll be striking out in no time," Willingham cracked.

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