Golden State Warriors head coach Steve Kerr said he is "devastated" for Kevin Durant after the star suffered an Achilles injury in Game 5 of the NBA Finals.

The Warriors stayed alive against the Toronto Raptors with a 106-105 win on Monday, however, the crucial victory was overshadowed by Durant's injury.

Durant – making his return from a calf injury after missing nine games – left Scotiabank Arena on crutches following an incident in the second quarter.

The 30-year-old appeared to re-injure his leg as he had to be helped off the court with less than 10 minutes remaining before half-time in Toronto.

Warriors president Bob Myers said Durant suffered an Achilles injury, with an MRI scheduled for Tuesday to determine the severity.

"I just told the team I didn't know what to say," Kerr said. "On the one hand, I'm so proud of them. Just the amazing heart and grit that they showed.

"On the other, I'm just devastated for Kevin. It's a bizarre feeling that we all have right now. An incredible win and a horrible loss at the same time."

Durant left the floor after he came up limping following a drive to the basket with a little more than 9:45 to play before halftime. He was then helped back to the locker room by team-mates Stephen Curry and Andre Iguodala.

A soon-to-be free agent, Durant scored 11 points on three-of-five shooting and grabbed two rebounds before exiting.

The Warriors ended up holding off the Raptors when Kyle Lowry missed a game-winning three-point attempt at the buzzer.

"We got stops. Our defense was bending down the stretch, but we didn't break," Kerr said. "The last stop was tremendous, amazing defense on that last play from all five guys."

The Warriors will host the Raptors in Game 6 at the Oracle Arena on Thursday.