ANAHEIM -- Vladimir Guerrero called it "nothing to worry about," and he was back in the Angels' lineup as their designated hitter on Tuesday night.
Guerrero was moved from right field to DH for Monday night's season opener when he reported some discomfort in his throwing arm after the team's pregame workout.
Guerrero said he could play in the outfield if necessary, adding, "It's early. No problem. I'm fine."
Manager Mike Scioscia also expressed no concern after watching his slugger drive in a run with one of his two singles in a 3-0 victory over the Athletics at Angel Stadium.
"It's a little muscular discomfort," Scioscia said. "We'll get him out in the outfield, but it won't be for a couple of days. I don't think it's going to be too long. Until he's capable of throwing a baseball, we'll DH him.
"He played catch yesterday, pregame throwing, and felt a little discomfort."
Bobby Abreu, who expects to play left field primarily this season, was in right field again on Tuesday, with Juan Rivera in left.
With his 19th career RBI on Opening Day, Guerrero now is the all-time leader in that department, according to Elias Sports Bureau. He had been tied with Frank Robinson and Jeff Kent with 18.
"Really?" Guerrero said, grinning. "I didn't know that. It's nice to hear."
Guerrero joined Lou Gehrig last season as the only players in history with 11 consecutive seasons batting at least .300 with 25 or more home runs.
Following winter surgery on his right knee, Guerrero said he's hopeful he'll get a step back on the bases and in the outfield. He has struggled with the knee the past two seasons and feels he's stronger than he has been since 2006.
"You've got to give him a little time with that, coming off surgery," teammate Torii Hunter said. "Give Vlad another month or so, and he'll be right where he wants to be."
Lyle Spencer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.