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08/30/12 5:32 PM ET

Ailing shoulder sends Span to disabled list

MINNEAPOLIS -- The Twins placed Denard Span on the 15-day disabled list following Thursday's 5-4 loss to Seattle because of a continued shoulder ailment. The move is retroactive to Tuesday, and Minnesota will make a corresponding roster prior to Friday's game against Kansas City.

An MRI performed on Span on Wednesday revealed a sprained sternoclavicular joint, which connects the clavicle to the sternum. He originally incurred the injury while trying to convert a sliding catch on Aug. 12 against Tampa Bay.

"We're going to give him this time and back away here," manager Ron Gardenhire said. "He's not getting better. Let him sit out for a few days, stay home, do some rehab, and go from there."

Span missed his third straight game on Thursday due to the injury.

The 28-year-old outfielder said on Wednesday -- before the Twins decided to place him on the DL -- the club would treat the situation accordingly with a day-to-day approach.

"I don't think there's really much I can really do," Span said. "They said it takes four to six weeks for it to heal -- if I just did nothing. But they don't seem to think me continuing to try to swing will make it worse. So hopefully get on this anti-inflammatory and get some more treatment, then maybe it'll be more bearable for me to at least play."

Plouffe heating up as he looks to regain timing

MINNEAPOLIS -- Trevor Plouffe went 118 plate appearances without a home run. Then he connected for a two-run shot off of Justin Vargas in the fourth inning of Minnesota's 10-0 victory against Seattle on Wednesday.

That blast was one of two hits on the night for Plouffe, who also ripped a two-run double to tie a career high with four RBIs -- perhaps a sign that the Twins third baseman is closer to recapturing the timing that made him one of baseball's hottest hitters earlier this summer.

Plouffe started at third base in Thursday's series finale and hit eighth, playing in his 17th game since returning from a bruised right thumb that kept him out for three weeks. The 26-year-old struggled initially, going just 2-for-33 in his first nine games back from injury.

But in seven games prior to Thursday, Plouffe hit .308 (8-for-26) with five RBIs.

Twins manager Ron Gardenhire said timing can be even more difficult to find after an absence for a hitter who uses a big leg kick, such as Plouffe.

"Guys that have a leg kick -- it's big," Plouffe said. "Guys that can flat-foot it and just use a little toe turn, it's easier for them. They can make adjustments. But when you pick up your foot, to get it down, yes, your timing can be screwed up for a while. Especially with layoffs. Your bat is a little longer. So a lot of things have to click."

From June 8-July 3, Plouffe hit 12 home runs in 99 plate appearances, demonstrating the type of run he can go on. After recording eight home runs and 31 RBIs in 81 games last season, he came into Thursday with 20 homers and 45 RBIs through 90 contests this year.

"But he's setting a little bit of a higher standard now," Gardenhire said. "He went off on that run when he was healthy. What's his limits? I don't know. I don't know how many he could hit if he stayed on a real good groove from day one of the season all the way through. Who knows?"

Sunday's pitcher likely among September callups

MINNEAPOLIS -- The Twins are expected to announce their first wave of September callups on Friday, including a starting pitcher for Sunday's game against the Royals.

Twins general manager Terry Ryan met with manager Ron Gardenhire on Wednesday to discuss which players they'll bring up on Saturday when the rosters expand.

The Twins need a starter for Sunday, as left-hander Scott Diamond is currently serving a six-game suspension for throwing a pitch near the head of Rangers outfielder Josh Hamilton last week.

"We'll have somebody here for that, definitely," Gardenhire said. "Somebody will be here to pitch. We don't exactly have him here right now, let's put it that way."

A likely candidate to make the start is right-hander Esmerling Vasquez, who has been impressive at Triple-A Rochester. The 28-year-old has posted a 2.78 ERA with 98 strikeouts and 38 walks in 100 1/3 innings.

Outfield prospect Benson undergoes knee surgery

MINNEAPOLIS -- Twins outfield prospect Joe Benson underwent surgery on his left knee earlier this week and will be shut down for three to four months, according to Twins assistant general manager Rob Antony.

Benson, ranked by MLB.com as Minnesota's No. 5 prospect heading into the season, had bone chips removed from his knee on Monday. But doctors found that there was a problem with the cartilage under his kneecap that required rest.

Antony, though, said Benson is expected to be ready for Spring Training.

"He'll do no strenuous activity for three to four months and then start his routine to prepare for Spring Training," Antony said. "The doctors said it should heal up fine."

Benson, 23, made his Major League debut as a September callup last season, hitting .239 with six doubles and a triple in 21 games. But he struggled in the Minors this year, batting a combined .202 in 76 games in Triple-A, Double-A and a rehab stint in Class A after undergoing surgery on his hamate bone in his left hand in late May.

Rhett Bollinger is a reporter for MLB.com. Read his blog, Bollinger Beat, and follow him on Twitter @RhettBollinger. Jordan Garretson is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.