BOSTON -- The Red Sox lost Kevin Youkilis in the top of the third inning of Monday night's game against the Indians due to a jammed right thumb.

Youkilis appeared to suffer the injury after lining to short in the bottom of the first. As he ran out of the box, Youkilis flexed his right hand in pain.

He told manager Terry Francona and trainer Mike Reinold he was fine to stay in the game at the start of the second inning. But the discomfort had worsened a bit later, forcing his early exit.

Victor Martinez moved to first base, and backup catcher Kevin Cash was inserted into the game and took over for Youkilis in the No. 3 spot of the order.

Abdominal issues land Cameron on DL

BOSTON -- For the past couple of months, Mike Cameron has been gritting his teeth and playing as much as he could despite a lower abdomen that was never even close to 100 percent. But on Monday, he and the Red Sox realized that it was getting to be a bit too much. The center fielder was placed on the 15-day disabled list, and his status for the rest of the season is unknown.

"It's just an opportunity to get me some rest, get my body a chance to kind of catch up," said Cameron. "It's been through a lot. I've been grinding."

Daniel Nava was summoned from Triple-A Pawtucket for his second stint with the team to replace Cameron. But Nava's second stay in Boston could be shorter than his first, as Jacoby Ellsbury is expected to be activated later this week.

Monday marked the third consecutive day Cameron wasn't healthy enough to play, so he underwent a medical examination during the day, after which the decision was made to place him on the DL for the second time this season.

The hope is that a couple of weeks of rest and rehab will do the trick and enable him to get through the remainder of the season. If his health doesn't improve during the time off, he will undergo season-ending surgery.

"It was a struggle," said manager Terry Francona. "He actually had been handling it unbelievably. I don't know how he's handled it for as long as he has. But the area has been getting a little bit bigger. There's some areas around [there] -- like the groin, and just higher up -- where [the inflammation] is starting to get a little bit bigger and make it harder for him to bounce back. We're going to put him on the disabled list and let him rest and get some treatment and see how that goes.

"If that doesn't go well, then certainly surgery is the next step. But we'd like to give him a chance to rest and see how he does. I think Cam feels the same way. That's what we'll do."

At this point, Cameron is staying positive. He is not ready to think about surgery.

"I'm not talking about that now," said Cameron. "That's something that's an option down the road, but it's not talked about right now. We'll just see how these two weeks go here, whether it's 10 [or] 15 days before we make a drastic decision on something."

Cameron is hitting .259 with four homers and 15 RBIs in 162 at-bats. The injury -- which first placed him on the DL from April 19 to May 24 -- has limited him on both sides of the plate.

"I think we were pretty honest," said Francona. "We were proud of him. It was sort of not an easy thing to do. You could see it. He was wearing it on his face a lot of times."

Eric Patterson started Monday's game in center, with Ryan Kalish playing left.

"I've given pretty much everything I've got," said Cameron. "I'm just on the DL. I'm not dying. It's one of those moments where I've got to kind of take a step back and kind of regroup. See what happens."

Ellsbury heads back to Pawtucket

BOSTON -- After conferring with center fielder Jacoby Ellsbury on Monday, the decision was made by the Red Sox that he's not quite ready to be activated yet.

Ellsbury played at Triple-A Pawtucket on Saturday and Sunday, going 4-for-9. He will return to Pawtucket on Tuesday, playing at least one more game in the Minors before reclaiming his spot at the top of Boston's batting order.

"We're kind of walking that line where we all know potentially what he can mean to us," said manager Terry Francona. "But he still feels it at times. We're trying to not get caught up in [a situation] like a [Mike] Cameron going down and then activating [Ellsbury] before he's ready. We're just trying to use the proper judgment, regardless of what's going on here. I think that's probably the only way to do it."

Ellsbury has played in just nine games for the Sox this year. He suffered a non-displaced fracture in several of his left ribs in a collision with Adrian Beltre in the sixth game of the season. Ellsbury came off the disabled list on May 22, but played just three games before learning he had suffered some more fractures.

Worth noting

Second baseman Dustin Pedroia continues to get his work in every day, but the last hurdle he has to clear before returning to action is running without any discomfort. ... Hitting coach Dave Magadan has been away from the team the past several days due to the death of his father. He is expected to return to the team on Tuesday. Staff assistant Ino Guerrero has been filling in for Magadan. ... First base coach Ron Johnson had to leave the team on Monday to tend to a family matter. Staff assistant Rob Leary took over for Johnson in the first-base coach's box.