SEATTLE — The Twins needed a reserve outfielder who can play center field. Clete Thomas tried but couldn't make enough contact at the plate. He's out, and now Erik Komatsu is in.

The Twins designated Thomas for assignment Friday and claimed Komatsu off waivers from the Cardinals. In 15 games with St. Louis this year, Komatsu, 24, hit .211 (4-for-19) with two walks and three runs. He will join the Twins in time for Saturday's game.

"Contact guy," acting Twins manager Scott Ullger said. "Can play all three outfield positions. And he can run a little bit, steal some bases."

Thomas homered in his Twins debut April 15, but he hit .143 with 16 strikeouts in 28 at-bats.

In 348 minor league games, Komatsu, an eighth-round draft pick by the Brewers in 2008, has a .302 batting average with 24 home runs and 166 RBI. He was traded to the Nationals last year as he hit .277 with seven homers and 48 RBI between Class AA Huntsville and Harrisburg.

He was selected in the Rule 5 draft last December by the Cardinals, so the Twins take on his Rule 5 rights. That means he has to stay on the 25-man roster for the rest of the season or must be offered back to Washington.

Erik Komatsu

The Twins were short on outfield options in the minors. Rene Tosoni or Brian Dinkelman could have been brought back from Class AAA Rochester, but both have been on the disabled list.

Ben Revere wasn't a candidate. One, he was just sent back down to Rochester and must remain in the minors for 10 days, barring an injury. Two, the Twins really want him to play every day. So they preferred to look at the waiver wire for options.

"We liked him and considered him for the Rule 5 draft when we selected Mr. [Terry] Doyle," Twins assistant GM Rob Antony said, referring to the righthander that was returned to the White Sox during spring training.

Komatsu is excited to be joining the Twins. He already has updated his photo on his website, erikkomatsu.lockerdome.com, where he touts some of his music.

Morneau not ready yet Justin Morneau didn't have any structural damage in his left wrist when he underwent a magnetic resonance imaging exam Tuesday in the Twin Cities. The slugger has since returned to the Twins, but there are no indications when he will play again.

In fact, all indications Friday were that he was shut down, as he remained in workout clothes as the rest of the team prepared to take on the Mariners.

"It's up to him to let us know when he can play," Ullger said.

Morneau, who did not meet with reporters before Friday's game, has not received any sort of painkilling injection.

"Not that it's not a possibility," Antony said. "But the doctors and trainers gave us an update [and] they did not talk about that. And when I talked to Justin the other day he didn't mention it."

Etc. • Ullger took over for manager Ron Gardenhire, who won't be with the club this weekend so he can attend his daughter Tara's graduation at Southwest Minnesota State. It's old hat for Ullger, who has filled in for Gardenhire after each of his 61 ejections, or when he's been sick or had family matters to attend to. "It's really no different," Ullger said. "We just focus and prepare and play the Seattle Mariners."

• Sean Burroughs cleared waivers and agreed to go to Rochester, where he can get steady at-bats. The veteran infielder could have turned down the assignment and become a free agent.

• It's unclear when Joe Mauer, who took a foul tip off his left knee Sunday, will start behind the plate again. Mauer was the designated hitter Friday.

• The Twins added Roy Larson as an extra bullpen catcher. Larson, from Eagan, played at rookie league Elizabethton in 2011 but was cut in spring training.