Jered Weaver (elbow) put on DL

ANAHEIM, Calif. -- Los Angeles Angels right-hander Jered Weaver will be out for at least a month after the ace broke a bone in his left elbow, casting a pall over the team's home opener Tuesday before it even began.

The Angels put Weaver on the 15-day disabled list, and the durable 20-game winner's non-throwing arm was in a blue sling while his teammates took batting practice before their Angel Stadium opener against Oakland.

"This is all new to me," Weaver said. "I've never broken anything before, and didn't really know how to take the news. It kind of was a shock at first, and now you've just got to play the waiting game, I guess."

Weaver left Sunday night's loss to the Texas Rangers early after jamming his non-throwing arm while dodging a line drive back to the mound. The Angels initially thought Weaver had only strained his elbow, but Weaver felt abnormal pain after the game, and an MRI exam on Monday unexpectedly revealed a fracture expected to sideline him four-to-six weeks.

"It's very disappointing, but I guess you've got to look on the bright side of things sometimes," Weaver said. "It's better earlier (in the season) than toward the end, but at the same time, it's very frustrating and disappointing."

Weaver's injury has sent the big-budget Angels scrambling after their 2-4 road start to a season of high expectations. Manager Mike Scioscia promoted hard-throwing right-hander Garrett Richards from the bullpen to replace Weaver in the rotation, and the Angels called up right-hander Dane De La Rosa, who just joined Los Angeles in a trade with Tampa Bay last month.

"It's extremely difficult to lose your ace, and Jered has been that for a long time here," Angels general manager Jerry Dipoto said. "He's a pivotal player for us. I feel like in some way the silver lining is it was his left arm, and there's more of a short-term definition to the injury than long-term. It's not as if we just found out he was out for the year or something along those lines. It's his left arm, and that's the positive here."

But Dipoto didn't sugar-coat the negatives, either. Weaver has been a mainstay in the Angels' rotation for the past seven seasons, starting at least 28 games in each of the past six campaigns while winning 102 games in his major league career, all with Los Angeles.

"I had no feeling it could be this bad," Dipoto said. "The results of the X-ray (in Texas) were negative for an obvious fracture. Unfortunately, the MRI didn't tell the same story."

Weaver had his first 20-win season with a 2.81 ERA last year, throwing a no-hitter against Minnesota along the way. He went 67-33 over the past four years, making 130 starts and establishing himself as one of baseball's top starters and the Angels' ace after John Lackey left for Boston in 2010.

Weaver has been an innings-eating starter throughout his career, but injuries were a big reason he finished third in the AL Cy Young voting last year despite tying winner David Price's 20 victories. Weaver missed three weeks last season with lower-back pain starting in May, and he also missed a start in September to rest tendinitis in his right shoulder.

"Hopefully we can keep him active and look forward to his recovery," Dipoto said. "I know he mentioned four to six weeks. He's going to do what he can to make sure it's closer to the four (weeks), but we're not going to push him. We're trying to win a championship here."

Weaver wasn't dominant in his first two starts this season, going 0-1 with a 4.91 ERA. Los Angeles lost two of three in each of its first two series against Cincinnati and Texas.

Richards has started 12 games over the past two years for the Angels while pitching mostly out of the bullpen, but he enjoyed an outstanding spring training. He had no spot in the rotation with returnees Weaver and C.J. Wilson backed by newcomers Tommy Hanson, Joe Blanton and Jason Vargas, but Weaver's injury could allow him to prove he's ready for a regular major-league starting role.

Richards is likely to get his first start of the season Saturday against Houston.

"Garrett is coming off a terrific spring, and he's throwing the ball extremely well," Dipoto said. "I don't know that anybody deserved the opportunity more than Garrett, and hopefully he can take the opportunity and run with it."

De La Rosa was acquired in a trade last month from Tampa Bay for right-hander Steven Geltz, and was ticketed for Triple-A Salt Lake before the Angels needed him.