The 7-footer tore cartilage in his right knee during a loss last week against Memphis.
Diop, the No. 8 overall pick in the 2001 draft, is averaging 2.8 points, 4.5 rebounds and 17 minutes. He has made three starts after making just one last season.
His improvement has been one of the few positives for Cleveland, which lost its eighth straight game Wednesday night. The 90-80 setback to the Los Angeles Clippers was the club's 33rd straight road loss, the third-longest streak in NBA history.