Rush, who was helped off the court after injuring his left knee in Friday's 104-94 loss to the Memphis Grizzlies, had an MRI Saturday and the diagnosis ends the 27-year-old forward's season.
Rush's agent, Mark Bartelstein, called the diagnosis "devastating."
From the start it was clear Rush's injury was bad, as the 6'6, 210-pound forward was seen in a lot of pain after Grizzlies forward Zach Randolph fouled him on an attempted dunk with 4:09 left in the first quarter of Friday's season opener. Rush landed awkwardly on his leg and immediately reacted as if something bad had happened.
Last season, Rush played in 65 of 66 games for the Warriors after coming over in a trade with the Indiana Pacers. Rush averaged 9.8 points and 3.9 rebounds in 26 minutes per game.
The Warriors' plan to replace Rush is unclear. Currently, Golden State could ask more from veteran Richard Jefferson and Draymond Green or apply for a disabled-player exception that would allow the team to sign or trade for a player who earns up to half of Rush's $4 million salary.