Clemens was placed on the DL on Jule 13 with tightness in his right groin, one of several injuries he has suffered this season. He also received a cortisone injection in his sprained right foot Friday, a day after his last rehabilitation start.
On Thursday, Clemens pitched for Class AA Norwich, allowing one run and five hits with no walks and seven strikeouts over seven innings against Binghamton. He turned 40 on Sunday.
He aggravated his injury after pitching five scoreless innings in a loss to Cleveland on July 12.
The righthander is 8-3 with a 4.02 ERA in 18 starts this season but has not recorded a victory since June 9 after winning eight of his first 14 outings. He was second in the American League with 126 strikeouts at the time of his latest injury.
Clemens is the active career leader in wins (288), starts (556), innings (3,996 2/3) and complete games (116). He needs one win to surpass Tommy John for sole possession of 21st place all-time.
To make room for Clemens, the Yankees optioned righthander Brandon Knight to Class AAA Columbus of the International League. Knight had no record and a 6.75 ERA in six relief appearances.