MINNEAPOLIS -- Right-handed reliever Lester Oliveros underwent Tommy John surgery on his right elbow Wednesday, Twins assistant general manager Rob Antony said.

Oliveros was scheduled to have bone chips removed from his elbow but doctors found ligament damage as well, so ligament replacement surgery was performed. Oliveros, who is expected to be out approximately 12 months, was aware of the possibility, according to Antony.

"They did the clean up and when they checked the gap they determined he needed Tommy John," Antony said. "He also had some large loose bodies in there removed that were causing irritation."

Oliveros, 24, was acquired from the Tigers in the trade that sent Delmon Young to Detroit last season. The hard-throwing right-hander posted a 2.42 ERA with 51 strikeouts in 48 1/3 innings between Double-A New Britain and Triple-A Rochester this season. He also made one appearance with the Twins, allowing one run over 1 2/3 innings.

Mauer shrugs aside waivers process as routine

MINNEAPOLIS -- Joe Mauer said his mother was at the Minnesota State Fair on Wednesday promoting Kemps Ice Cream but had a feeling the conversations dealt more with her son reportedly being placed on waivers.

FOX Sports' Ken Rosenthal originally reported Tuesday night that the Twins placed Mauer on waivers. No team claimed him.

"I just got a lot of phone calls and text messages and things like that," Mauer said. "From my understanding of the whole thing, it won't be the first time or the last time. It's part of the game. I was a little surprised at how much coverage it got."

Mauer generally shrugged off the process as routine, a sentiment echoed by teammate Justin Morneau. Morneau reportedly was claimed by the Dodgers on waivers earlier this month, but the two teams did not work out a deal.

"It's something that happens every year," Morneau said. "Usually you don't hear about it. I guess it has to do with the position that we're [the Twins] in, why you hear about it. Everybody in here has been run through it at some point. We've all been run through it in the past. It's a non-issue."

Mauer served as Minnesota's designated hitter on Wednesday and hit third against Seattle.

"I signed here because this is where I want to play. Obviously that helps," Mauer said of the no-trade clause in his contract. "I'm not going to speculate on anything. This is just part of the game and I'm more worried about getting some runs for our pitching tonight."

Span day-to-day after MRI reveals sprained joint

MINNEAPOLIS -- Denard Span was absent from the Twins lineup on Wednesday for the second straight day, but finally learned specifically what is ailing him.

An MRI Wednesday morning revealed a sprained sternoclavicular joint, which connects the clavicle to the sternum.

"I guess we're going to take it day to day," Span said. "It's going to be painful. It's kind of just going to be based on how I feel. There's going to be days when I can go out there and swing, and there's going to be bad days."

Ben Revere took over Span's normal posts as leadoff hitter and center fielder in Wednesday's game against the Mariners. Chris Parmelee started in right field.

Span said he will be treated with anti-inflammatories, but the injury will likely nag at him for the remainder of the season.

"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."

Diamond begins serving six-game suspension

MINNEAPOLIS -- Scott Diamond dropped the appeal of his six-game suspension from Major League Baseball and instead began serving the sentence on Wednesday.

The Minnesota left-hander said he came to the decision after receiving advice from the Players Association.

"Just from looking at it that way, we just decided the best course of action was probably to just move the appeal and serve out the sentence," Diamond said. "It's a little frustrating the way it all played out, but at the same time, that's the way it happened. I can't deny what happened."

The suspension was handed out after Diamond was ejected from Minnesota's game last Thursday against the Rangers after throwing behind Josh Hamilton. That exchange came a half-inning after Texas' Roy Oswalt hit Joe Mauer in the back with a 3-0 fastball with two outs.

Diamond is a team-leading 10-6 this season with a 3.21 ERA in 21 starts.

"I want to continue to be able to contribute," he said. "That's the biggest thing. I stand by my actions -- what happened, happened. That's the way it all played out, obviously. It's just disappointing that I won't be able to keep the same routine and be able to come back out and make another start in five days."

Twins tab seven prospects for Fall League squad

MINNEAPOLIS -- Seven players in the Minnesota Twins organization will take part in this year's Arizona Fall League, playing with the Peoria Javelinas.

The Twins will send right-handed pitchers Kyle Gibson and Michael Tonkin, as well as left-handers Logan Darnell and Caleb Thielbar to Arizona. They will be joined by catcher Chris Hermann and outfielders Evan Bigley and Nate Roberts.

Gibson -- a first-round pick of the Twins in 2009 -- is currently with Triple-A Rochester and in his first season since coming off Tommy John surgery last November. He lost his only start with the Red Wings, giving up four runs in three innings against Buffalo on Aug. 25. He posted a 2.57 ERA in two rehab starts with Class A Fort Myers earlier this month.

The Javelinas will play their home games at Peoria Sports Complex and will be coached by Dusty Wathan, who currently manages the Reading Phillies, Philadelphia's Double-A affiliate. Prospects from the Mariners, Padres, Phillies, and Reds will join the Twins' seven players with the Javelinas.