ANAHEIM — Sunday was a day of rest for some A's regulars, and that made it a day of opportunity for Adam Rosales.

Getting the start at second base, and drawing his first at-bats of the season, Rosales drove in four runs to key the A's 9-4 victory over the Los Angeles Angels before a crowd of 40,601 at Angel Stadium.

Much was written about Rosales' high-energy style of play before Oakland obtained him from Cincinnati in February. Now the A's are experiencing it for themselves.

In his first at-bat, Rosales lined a 1-0 pitch from Joe Saunders for a solo homer in the second inning. Sprinting immediately after contact, Rosales seemed to reach first base before the ball cleared the left-field wall.

"He's someone who probably needs to take a nap," A's starting pitcher Dallas Braden said amusedly.

"He plays like he hasn't slept in four days. I relish players like that. He doesn't know any other speed. You get somebody to play with that kind of energy, it gets you going."

It's early, but the A's are a confident bunch after opening the season 5-2 against division foes Seattle and Los Angeles. Today marks their fifth consecutive day atop the American League West. The last time they occupied first place was May 12, 2008.

With a day game after a night game, A's manager Bob Geren rested catcher Kurt Suzuki, designated hitter Eric Chavez and left fielder Travis Buck. Starting second baseman Mark Ellis served as DH.

Joining Rosales in the lineup were reserves Jake Fox at catcher and Eric Patterson in left field.

Braden (1-0) gave up two runs in the first, but he and Saunders (0-2) both found a groove, with each retiring 13 straight at one point.

The A's trailed 3-1 but took the lead with a three-run seventh.

Ellis' ground-rule double scored Ryan Sweeney. After Kevin Jepsen relieved Saunders, Rosales came up with runners on second and third and went the other way for a two-run single to give the A's a 4-3 advantage, lining up Braden for the victory.

Oakland scored five times in the final two innings to break the game open.

Rosales played all over the infield in 87 games with the Reds last season. The A's will ask the same of him, and he said he's learned how to be ready when called upon.

"The experience I had last year has helped me this year," he said. "I feel more calm."

Geren echoed Braden's sentiments, saying Rosales' enthusiastic play is infectious.

"It just does something to the other guys," Geren said.

"And he's not trying to show the other team up. That's just his natural style of play. He runs on a walk."

Braden, who struck out a career-high 10 in his first start, settled down after his shaky beginning Sunday and lasted six innings, allowing three runs on five hits.

Rookie Tyson Ross took over in the seventh, charged with protecting a one-run lead.

The A's added plenty of cushion for him, and Ross worked the final three innings to notch his first career save.

Geren has said he'll be careful to give the right-hander plenty of rest between outings. Ross made the team as a reliever but had been solely a starter before this season.

He allowed his first career run on Juan Rivera's homer in the ninth.

TODAY: A's (Justin Duchscherer 0-0) at Mariners (Ryan Rowland-Smith 0-0), 3:40 p.m. TV: CSNCA. Radio: 860-AM; 1640-AM