The Yankees placed Aroldis Chapman on the injured list because of a leg infection.
Speaking before the Yankees took on the Oakland A's in the third game of a four-game series, they said the problem was with a tattoo.
The veteran, who is no longer the closer in New York, has not pitched in over a month. Chapman is expected to pitch again this year.
The Yankees have been short-handed throughout the summer. New York won't call anyone up this weekend because Clay Holmes, who is on the injured list, will be back next week.
Chapman has a 4.70 earned run average this season and a 1.44 WHIP. Chapman is going to be a free agent this year.
The Yankees entered Saturday with a nine-game lead for first place in the American League East, and they had a five-game winning streak that included a sweep of the New York Mets.