The only one not surprised by a sudden change in starting pitchers may have been Karstens himself. The 24-year-old right-hander stepped in and didn't miss a beat, scattering two hits and striking out four Devil Rays over three scoreless innings in the Bombers' 5-1 win.
"It's nice just to give them that liberty," Karstens said. "If I have to do it, I can do it. If they want to use me [as a spot starter], they can."
The effort took Karstens -- who was scheduled to pitch in relief of Pavano -- from his usual pregame rituals of arm warming and repeating iPod shuffles to the mound, where his second victory of the Grapefruit League season took shape.
Making his bid for a role on the Yankees' projected 12-man pitching staff, Karstens has now pitched five scoreless innings to open the month, allowing four hits, no walks and striking out five.
"He's quietly pitching pretty well, isn't he," said manager Joe Torre. "He's been very impressive. His velocity was more than it was when we saw him last year."
Karstens appeared in eight games (six starts) with New York last season, going 2-1 with a 3.80 ERA. He had struggled mightily at Triple-A Columbus earlier in the year and was demoted to Double-A Trenton after beginning the season 0-5, but rebounded to go 6-0 at Trenton and eventually work his way into position for his first big-league callup.
"I think I matured a little bit, to know that I can't do any more than what I'm capable of," Karstens said. "I can't pitch like [Phil] Hughes or [Steven] White or [Darrell] Rasner. I've got to pitch how I pitch."
Karstens prefers starting, but he understands that those slots are in short supply with the Yankees. He said he would be fine with a role as the Yankees' long reliever and spot starter, which could be his best shot to make the team.
"The big leagues are the big leagues," Karstens said. "You ask anybody in here. As long as you're contributing somehow to help them win, that's all that matters."
For that task, Karstens would be in competition mainly with Rasner, a 26-year-old right-hander who has also compiled five scoreless innings in two spring appearances.
"He seems to be pretty aware of what he can do," Torre said. "He really doesn't complicate things for himself, and I think that's really going to help him in whatever role he has to take on. We're not sure what we're going to do leaving here, but he certainly has made a case for himself."
Bryan Hoch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.