Mitch Maier was called up from Triple-A Omaha to replace him on the roster and was in the starting lineup against the Tampa Bay Rays on Thursday.
Maier got the news early Thursday morning from Omaha manager Mike Jirschele at Las Vegas where the O-Royals were in the middle of a four-game series.
"I was sleeping," Maier said. "I was awake as soon as I saw who was calling me. The manager doesn't normally call at 7 a.m. for no reason."
Royals manager Trey Hillman immediately inserted Maier in center field and in the ninth spot in the lineup, where Gathright had been the previous three games.
Mark Teahen was not in the outfield for those games as Hillman said he was nursing a stiff back. David DeJesus was in left and Jose Guillen in right.
Maier, 26, was batting .316 with nine homers and 41 RBIs in 85 games for Omaha. A left-handed hitter, he made his Major League debut in September 2006 and played in five games. He was 2-for-13 with two walks.
"I have a little bit of experience so, hopefully, the nerves are gone," Maier said. "I've had a hit in the big leagues before so I'm not going to go up there pressing with an I gotta get my first hit kind of thing."
A former catcher and third baseman, Maier has developed into an excellent center fielder. He's been batting leadoff for Omaha, although that's not considered his future.
"I didn't mind it at all," Maier said. "It got some getting used to. I had to refine my approach a little bit and be more patient, but it worked out well."
Gathright, who apparently injured his shoulder diving for a ball on July 5 at Tampa Bay, was told that rest was the best cure. He's not expected to miss more than 15 days.
"We think it happened when I dove for that ball in Tampa Bay. At least that's what the video shows and the pain started the day after that," Gathright said.
For the past week and a half or so, it's bothered him primarily while at bat.
"When I swing and miss, it's kind of hard to be ready to swing for the next pitch," he said.
Gathright previously had battled problems with his left shoulder which, on occasion, pops out of place temporarily. That happened on May 17 at Florida when he and DeJesus collided in mid-air with DeJesus while chasing a long drive in the outfield. He finished that game, but missed the next three.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.