Though Phelps' stamina has not been built up for a spot start or long-relief role, Yankees manager Joe Girardi said that he could use Phelps "as a one-inning guy, maybe a little bit more than that."
"It's nice to be here in this fight right now," said Phelps, who is 6-5 with a 5.01 ERA in 18 appearances (12 starts) for the Yankees this season.
Girardi said that Phelps has faced some professional hitters under simulated conditions down in Tampa, Fla., including Travis Hafner, so he might have to be trusted right away against the Red Sox.
"I'm not so sure we have a chance to be patient with him. He might be thrown right in the fire," Girardi said.
In a corresponding roster move, the Yankees transferred shortstop Derek Jeter to the 60-day disabled list.
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.