Chapman was forced from Tuesday's game against the Marlins with left knee discomfort, Coley Harvey of ESPN.com reports.
It's the same knee and same area as the tendinitis that has bothered Chapman throughout the season, which is now a huge concern for the Yankees. The veteran left-hander will undergo an MRI to help determine the severity of the issue, which last flared up in early July. The specifics remain unclear, but a worrying sign cropped up post-game when Chapman said the pain experienced Tuesday was "more than usual," Erik Boland of Newsday reports.