Garrett Richards felt some cramping in his biceps, as if someone had punched him in his pitching arm.
The Los Angeles Angels are taking no chances after going without him most of last season, yet manager Mike Scioscia still hopes the right-hander can make his next start.
Richards pitched beautifully while making his first appearance in 11 months after an elbow injury cut short his 2016 season, but left abruptly in the fifth inning with biceps cramping before the Angels beat the Oakland Athletics 5-0 on Wednesday night.
"Nothing serious. My arm feels good. I felt good tonight, elbow feels fine, shoulder feels fine," he said. "It was just kind of a long inning and it just kind of stiffened up a little bit. There's no red flags or anything, just something that flared up. ... Everything kind of moves on as planned."
Scioscia and the training staff rushed to the mound after Richards threw a 94 mph called strike to Matt Joyce with two outs in the fifth. Richards was removed from the game, one out shy of being eligible for the win, and slugger Albert Pujols put an arm around the pitcher in the dugout.
The team announced he came out for precautionary reasons. Afterward, Richards went through strength tests with no issues. He will be examined by team doctors back in Southern California.
Richards struck out four and walked one, allowing three hits in 4 2/3 innings. JC Ramirez (1-0) worked 2 2/3 innings for the victory.
"That's a great first step for Garrett," Scioscia said.
Mike Trout hit an RBI single to back Richards, the Angels' opening day starter a year ago. He pitched for the first time since last May 1.
Danny Espinosa hit a two-run single one night after delivering a deciding three-run homer, and Andrelton Simmons doubled home a run in the second against Jharel Cotton (0-1).
The 25-year-old Cotton, who came to the A's in a trade-deadline deal last year that sent Rich Hill and Josh Reddick to the Dodgers, can feel good about striking out Trout twice on seven pitches.
"He's got such a wide gap between his fastball and his breaking stuff," Oakland manager Bob Melvin said. "At times you almost have to guess with him a little bit, especially when he's spotting his fastball and he's got decent velocity with it."
Cotton allowed eight hits and five runs, struck out four and walked two in 4 1/3 innings. This marked his first major league loss after going 2-0 over five starts in 2016.
Frankie Montas - who arrived in the same trade as Cotton - pitched 2 2/3 scoreless innings in his A's debut.
The AL West rivals had split the first two games of the season.
Angels: RHP Matt Shoemaker came out fine from Tuesday's outing, his first in exactly seven months since being struck in the head by a line drive and needing surgery. "I think it's good he can exhale. He got the first one out of the way," Scioscia said. "I think like any starter, your first start is like opening day. It's probably, obviously, more focus on it to what happened to Matt last year. He was fine." ... Scioscia plans to start Carlos Perez behind the plate in the series finale Thursday afternoon to spell starting catcher Martin Maldonado.
Athletics: RHP John Axford was placed on the 10-day DL, retroactive to Sunday, with a strained right shoulder. He experienced tightness after throwing a curveball warming up Tuesday night. Axford had no issues leading up to the injury. "None, zero," Melvin said. "It was a complete surprise not only to us but to him." RHP Jesse Hahn was recalled from Triple-A Nashville and will be used "for a little bit more length to have a starter back there," Melvin said. ... A's starter Chris Bassitt threw to hitters for the first time since Tommy John surgery last May. He threw 25 pitches, all fastballs, after his warmup. "The first time you had nerves and the first time you had adrenaline in nine months. Good feeling to have," said Bassitt, who threw about 10 bullpens before Wednesday's session. Bassitt is scheduled to pitch to hitters again Sunday at Class A Stockton and expects to be pitching in rehab games next month.