"Someone has got to step up. That's why you prepare," Girardi said. "We have eight or nine starters going in Spring Training because you know it's very possible. In today's game you'd better be deep in your starting rotation, because it's going to take more than five."
Capuano arrived at George M. Steinbrenner Field on crutches on Thursday after receiving a platelet-rich-plasma injection, intended to speed healing. He acknowledged that he will begin the season on the disabled list.
"It's disappointing. I'd been feeling really good physically and throwing the ball," Capuano said. "It's a setback, but I've had little injuries in the past, and I know how to work through them. It won't be too long."
While pitching for the Brewers in 2004, Capuano missed approximately a month with a similar strain in his left quadriceps. Feeling that sensation in his right quad on Wednesday, Capuano immediately knew that he would have to exit the game.
"Anyone who has ever pulled a muscle or something running, you know pretty quick that something is wrong," he said. "There wasn't a question of trying to continue to go on at that point. I could feel it."
In Capuano's absence, the Yankees will evaluate their starting options from a group that includes Adam Warren, Esmil Rogers, Chase Whitley, Bryan Mitchell and non-roster invitee Scott Baker, all of whom have started games this spring.
Pitching coach Larry Rothschild has also been talking about using a sixth starter at times in April and May, which could create more opportunities to help at the big league level. Girardi said that it is too soon to break down the competition.
"I don't think it's really fair to judge right now, and I've told them that," Girardi said. "Let them get another start under their belt, and then you'll start really looking."
Bryan Hoch is a reporter for MLB.com. Follow him on Twitter @bryanhoch and read his MLBlog, Bombers Beat. This story was not subject to the approval of Major League Baseball or its clubs.