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ANAHEIM, Calif. -- The Oakland Athletics had more than their share of comeback road victories en route to a surprising AL West title last season, and they picked up yet another to spoil the Angels' home debut.

Pinch-hitter John Jaso had a go-ahead, three-run homer in the seventh inning, and the A's blew a four-run lead before rallying to beat Los Angeles 9-5 on Tuesday night in the majors' final home opener.

Brandon Moss had three hits and drove in four runs, delivering an early two-run single before adding a two-run homer after Jaso's shot. Coco Crisp also hit his fourth homer for the A's, who have won six straight after an 0-2 start.

"That's part of who we are," Oakland manager Bob Melvin said. "We feel like we always have a chance to come back, so we keep grinding through the whole thing, and sometimes we have a chance."

Oakland led 4-0 early, but fell behind on Howie Kendrick's RBI triple in the sixth. After the A's put two runners on in the seventh against Kevin Jepsen (0-1), Jaso's drive landed on top of the chest-high fence down the right-field line, skipping into the seats for his first homer. Two batters later, Jepsen yielded Moss' first homer.

"It was just a crazy game right out of the gates," Jaso said. "It seemed like every inning was a get-out-of-a-jam inning. ... It was a wall-scraper, right there on the shortest part of the fence. I didn't think it was going to get out, but it got out."

Josh Hamilton went 0 for 4 with a sacrifice fly in his home debut for the big-budget Angels, who dropped to 2-5. Kendrick had three hits and capped Los Angeles' three-run rally in the sixth with his triple off Ryan Cook (1-0).

Albert Pujols reached base four times for the Angels, whose first homestand already was off to a rocky start before C.J. Wilson's mediocre outing and the bullpen's struggles: Staff ace Jered Weaver was ruled out for at least a month with a broken left (non-throwing) elbow Tuesday morning.

The hard-throwing Jepsen had two outs, but couldn't finish off Jaso.

"It was in the middle of the plate, and obviously it wasn't supposed to be in the middle," Jepsen said. "His bread and butter is hitting fastballs, and in situations like that, sometimes you get burned."

Hamilton was greeted in right field by fans holding up "Hamiltown" signs for his first game at Angel Stadium since he left the Texas Rangers last winter to sign with their AL West rivals.

The $125 million slugger struck out on three pitches with the bases loaded in his first plate appearance and grounded weakly back to the mound with the bases loaded again in the fourth. But Hamilton also made a diving catch in right field in the fifth inning before tying the game with his sacrifice fly in the sixth.

Wilson is the Angels' highest-profile starter in Weaver's absence, but the left-hander allowed six hits and four runs over six innings, getting through a 43-pitch first inning before leaving with a lead.

"You're always going out there pitching to win and trying to pitch a shutout, regardless of whether everybody's pitching good or pitching bad," Wilson said. "We're all just super-competitive people within ourselves. I was determined to have a better start than I did (last week) in Cincinnati, and it turned out to be the same result."

Mark Trumbo had an early RBI single in his third straight multihit game, but he also grounded out twice with the bases loaded for the Angels, who had 13 hits and stranded 13 runners.

Angels shortstop Erick Aybar had two singles before leaving in the third inning with a bruised left heel after stretching to reach first base while beating out an infield hit.

Josh Reddick sat out for the A's after spraining his right wrist while crashing into a wall in Houston last weekend. Second baseman Scott Sizemore then left in the fourth after spraining his left knee while chasing Mike Trout's short outfield fly.

Sizemore is headed back to the Bay Area on Wednesday for an MRI exam on his surgically repaired knee.

"Hopefully, it won't be anything too serious, but right now I don't know," Sizemore said, his leg immobilized. "Scar tissue is probably the best-case scenario with what I felt."

Jarrod Parker had his second straight rough start for the A's, yielding nine hits and three walks while failing to get out of the fourth inning.

Game notes

Oakland made three errors in its first seven games before committing two more in the sixth inning. ... Los Angeles' third-inning rally could have been even bigger, but Pujols made a huge baserunning blunder on Hamilton's flyout to center, running several steps past second base and failing to get back to first before Oakland easily doubled him off. ... Los Angeles recalled RHP Dane De La Rosa to take Weaver's roster spot, and he made his Angels debut with a scoreless ninth inning.