Green was taken out of Friday's start in the second inning due to right elbow pain, Mark Feinsand of the New York Daily News reports.
The extent of Green's setback will not be determined until he is further examined by the Yankees' medical staff, but the early diagnosis is hardly promising, given that elbow pain is typically the first sign of an injury that could require Tommy John surgery. The Yankees figure to release more details on Green's status after more tests are done.