BOSTON -- The Rays already have a team-high 10 players on the disabled list and received more bad news on Friday with Brandon Guyer needing season-ending shoulder surgery.

"Guyer is going to end up needing surgery," said manager Joe Maddon. "It's his shoulder. I'm not exactly sure what's going on with that."

The outfielder will have surgery to repair a torn labrum in his left shoulder (non-throwing) on Thursday.

It's the worst-case scenario for the Rays, who were expecting Guyer to possibly return next month. Instead, he's out for the year.

"When it happened we just didn't know," Maddon said. "It was one of those things that when you talked to him about it there was never a strong feeling one way or the other, let's get more opinions, and then finally it's gotten to this point. I didn't know what to think when I first heard about it."

Maddon was not sure how long the expected recovery time would be.

"It's not brief," he said. "I don't know."

Guyer is one of four outfielders on the disabled list, along with Desmond Jennings, Sam Fuld and Brandon Allen. They've combined to miss 86 games this year.

Jennings, who missed his 13th game on Friday with a left knee sprain, is likely to begin a Minor League rehab assignment next week.

"It looks like he might be able to get something going by the middle of next week," Maddon said. "When we go back home on Monday, [he'll begin] more concerted baseball activity in a practice sense and then get out on a field and play in a game, probably by the middle of next week."

Guyer played in just three games this year. He homered in his last game, a solo shot in a 5-3 loss to Baltimore on May 12. Guyer played in 15 games for the Rays in 2011, his first season in the Majors.

The development could provide an opening for Hideki Matsui, who signed a Minor League contract on April 30. In nine games with Triple-A Durham entering Friday, Matsui was 4-for-33 with four RBIs. Still, it could take some time for Matsui to return to the Majors.

"He's doing well, he's not quite ready yet, but he's getting real close," Maddon said. "That's just the general consensus. He's feeling good, he's getting better, he's seeing the ball, but he's just not quite ready yet."

Maddon keeping Pena atop lineup for now

BOSTON -- Manager Joe Maddon isn't afraid to plug his sluggers into the leadoff spot to break a slump, and it's working again, this time with Carlos Pena.

The first baseman was back in the leadoff role in the series opener against the Red Sox on Friday, his third consecutive game at the top of the order.

"It's cool. I like it because it's different," said Pena, who grew up in Haverhill, Mass., and attended college at nearby Northeastern University. "I'm just rolling with it."

Pena went 3-for-8 with one home run, one double and three RBIs in his first two games batting leadoff. He'd been in an 0-for-17 skid prior to moving up the order.

So far, the slugger admits he's fond of his new role.

"Everybody does enjoy it," Maddon said. "It's different and he likes it, so I know he's excited about it. I know he's not up there just trying to get hits, he wants to get on base, he wants to set the table. And if he's thinking that way, I expect to see more hits."

Maddon used the same tactic last season when Evan Longoria and Matt Joyce fell into slumps. All three players homered in their first game leading off. Entering Friday, the trio had combined for a .481 average (13-for-27) from the top of the order.

So why does this strategy work?

"We get them to think differently about themselves and think differently about their approach to hitting and what they're trying to do, accept their walks, think of the middle of the field and not just try to drive the ball," Maddon said. "Primarily, that's it and when you do that, they just have a different outlook on the day. Normally, once you get them re-established you move them back down to where they're used to being, but for right now it's worked out pretty well."