Left-hander Ron Mahay, on the disabled list with plantar fasciitis in his left foot, might be ready to go by Tuesday.
"I'm not sure, but I hope [he] will," manager Trey Hillman said. "He's felt better with the exercise program he's been on. It would be nice to have his services."
The Royals also can bring back two other veteran lefties, Jimmy Gobble and John Bale, who have been on injury rehabilitation assignments with Triple-A Omaha. The rosters can be expanded on Monday, an open date, and the Royals will be adding players.
"I'd say between four and six, when you consider guys that are legitimate callups along with guys that have been rehabbing," Hillman said.
Minor Leaguers who get a September callup might not get extensive playing time, however.
"With what we've gone through this season and, obviously, our lack of winning percentage, I think we're evaluating even our guys that are still here," Hillman said. "With guys that come up, we'll fit 'em the best way that we can. Some of the guys are going to be here more for the experience than the playing time."
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.