Phelps, 27, has been out with elbow inflammation since last month. He has gone 5-5 with a 4.24 ERA and 89 strikeouts in 26 games this season, including 17 starts.
Fellow pitchers C.C. Sabathia and Ivan Nova are out for the season due to injuries, and Masahiro Tanaka and Michael Pineda have also missed significant time.
The Yankees were 75-69 entering Friday and 10.5 games behind the Baltimore Orioles for first place in the American League East. New York is four games behind the Detroit Tigers for the final Wild Card spot.
- Paul Palladino