ANAHEIM -- Center fielder Milton Bradley was a late scratch from Friday's lineup against the Los Angeles Angels due to soreness in his right side.

Bradley took batting practice before the game but had been sore for a couple days, according to A's manager Bob Geren, who recommended to Bradley that he take the night off as a precaution.

Nick Swisher switched from first base to center, and Todd Walker was inserted at first base for his first start of the regular season.

The A's no doubt will monitor Bradley closely considering he's missed significant time throughout his career with various injuries. A strained right oblique (side) muscle contributed to the first of Bradley's two stints on the disabled list last season. He also had a sprained right knee during that first stint and missed six weeks.

"I don't think so," Geren said when asked if this oblique injury is similar to last year's. "I hope not."

The A's can ill afford the switch hitter to miss much time considering he's taking the place of regular center fielder Mark Kotsay, who is likely out until June while recovering from back surgery.

Bradley is hitting .375 and has looked sharp in center after playing right field all of last season for the A's.

Oakland's Nos. 4, 5 and 6 hitters in the original lineup -- Mike Piazza, Eric Chavez and Mark Ellis -- all were bumped up a spot after Bradley was scratched, with Walker batting sixth.

Position-hopping is nothing new to Swisher, though he had played exclusively first base in the season's first four games because Dan Johnson is on the disabled list. Before the game, when Swisher still was slated to play first, he was asked if he expected to play much outfield in the coming weeks.

"That ain't my call," Swisher said. "When the time comes and I need to (play outfield), I'll be ready."

Run producer

Mark Ellis, RBI man? The second baseman came into Friday's game leading the majors in that category with eight.

That's part of the reason why he found his name penciled in to bat sixth Friday. He had batted ninth in the A's first three games and eighth Thursday. And when Bradley could not play Friday, Ellis moved a spot higher and hit fifth. "I hit everywhere except fourth and fifth last year, I'm used to it," Ellis said of bouncing around the batting order. "It doesn't make a big difference to me -- bottom, middle, wherever."

Ellis' career high in RBI is 52, a number he's finished at each of his last three full seasons. He got a good laugh of his name topping the RBI charts.

"I'm sure that won't last too long," he said.

Short hops

Catcher Jason Kendall got his first day off, with Adam Melhuse starting behind the plate. With Kendall sitting, Shannon Stewart hit leadoff for the first time in 2007. ... A loud chorus of boos greeted Piazza as he stepped to the plate. Angels fans no doubt remember Piazza from his days wearing Dodger blue, and his ninth-inning home run off Francisco Rodriguez in Thursday night's win didn't do anything to endear him. ... Geren said before Friday's game a decision had not been made on whether a pitcher might be skipped in the rotation on the team's first homestand, which features two off days. "We wanted to see how Chad (Gaudin) did (Thursday) and how Joe (Kennedy) does tonight."

-- Joe Stiglich