CLEVELAND – Trevor Larnach decided to extend his stay in Philadelphia for a bit.

The Twins outfielder traveled there Monday to seek a second opinion on his core muscle injury, which is similar to a sports hernia. The specialist recommended an operation, which the 25-year-old planned to undergo Tuesday.

Larnach made a diving catch with the Twins in Arizona on June 19 and felt a sharp pain in his groin. That area had already been mildly bothering him for a couple weeks, but the play exacerbated it. The Twins put him on the injured list Saturday, and now he will be out for about six weeks recovering from the bilateral surgical repair.

President of Baseball Operations Derek Falvey said Larnach and the doctors considered treatments such as rest or an injection but decided surgery was the best course.

"I would imagine it's six to seven weeks or something like that to get back to major league baseball games, that's what's been reported to us," Falvey said. "But again, probably have to do the surgery and get on the back end and make sure we feel good about how it went."

Larnach is hitting .231 in his second MLB season, with five home runs, 18 RBI and 13 doubles.

Polanco progressing

A setback slightly delayed second baseman Jorge Polanco's return from his first MLB IL stay. Manager Rocco Baldelli had said Polanco could return from his low back tightness on Monday in Cleveland, though that didn't end up happening.

"He had a day where he had some minor increased soreness and didn't do baseball activity," Baldelli said of this past Saturday. "He's going to go and test it out again [Monday] and see how he is moving around."

Polanco had a full workout Monday — throwing, fielding groundballs, taking batting practice on the field and in the cage for 50 swings on each side — and felt great. The Twins will evaluate him more Tuesday, but he seems likely for a comeback at some point in this Cleveland series, with four more games in three days.

Doubleheader order set

The Twins will start lefthander Devin Smeltzer is pitching the first game of Tuesday's doubleheader, and righthander Josh Winder will start the second game.