Just a few hours after he sent a public message of support for teammate Kevin Durant, who will miss the 2019-20 season with a ruptured Achilles tendon, Klay Thompson tore his ACL. While Thompson's injury didn't look good, any optimism that it may not be that bad was squashed in the early morning hours when his agent told ESPN it was torn. Shortly afterward the team confirmed the news:

The injury occurred with less than three minutes in the third quarter after Thompson was fouled by Danny Green while going up for a breakaway dunk.

Up until that point Thompson was having a great night, with 28 points in 32 minutes. He finished with 30 after capping his game/season by hitting a pair of free-throws on his bad knee. Had he not returned to take those shots he would not have been allowed to return to the floor.

Head coach Steve Kerr said that Thompson told him he'd be back after a two-minute rest, and at the time Golden State led 85-80. They'd end up losing 114-110, giving Toronto their first NBA title in franchise history:

Instead he ended up leaving the arena on crutches:

Thompson did jumping jacks in the tunnel prior to getting on the line. Draymond Green said that that didn't surprise him. “It does not shock me one bit. Klay is crazy, to say the least,” Green said, according to The Mercury-News. “He loves to play basketball and no matter what, he’s got he’s going to try to be out there on the floor.”

Thompson is set to become an unrestricted free agent in the offseason, though most/all year it looked like a done deal that he'd be staying put.

If you've watched sports for awhile you know the basic timeframe for an ACL recovery. But, officially, the Mayo Clinic puts the average return for an athlete between eight months and a year.