Suns guard Brandon Knight suffered a torn ACL in his left knee last week while playing basketball in Florida.
Suns team physician Dr. Tom Carter determined that Knight will require surgery, and he is expected to miss the entire 2017-18 season.
The injury is the latest injury blow for Knight, who has struggled with injuries since being traded to Phoenix from Milwaukee in 2015.
He missed 46 of his first 109 games through injury and both his first two seasons in Phoenix ended early thanks to injury problems.
Knight, 25, averaged a career-low 11.0 points, 2.4 assists and 2.2 rebounds over 54 appearances in 2016-17, his sixth NBA season and third with the Suns. He is under contract for the next three seasons at approximately $44 million.