Suns center Alan Williams partially tore his meniscus after landing on a teammate's foot during a workout, according to an ESPN report.
Williams is expected to undergo an MRI on Saturday, Chris Haynes reported.
The Suns re-signed Williams to a three-year deal worth $17 million in July.
It was reported on Wednesday that center Alex Len would sign his qualifying offer with the Suns next week.
Williams, 24, was among Phoenix's best stories last season. The 6-8 forward – a Phoenix native – spent most of the first half on the bench, gaining attention for his cheering and support.