Kawhi Leonard has vowed to be ready for game six of the Western Conference semi-finals, after being struck down by injury against the Houston Rockets.

Leonard missed much of the fourth quarter and overtime in Tuesday's 110-107 OT win due to knee and ankle problems.

But the All-Star will be fit for Thursday's trip to Houston, with the Spurs leading the NBA playoff series 3-2.

"Yeah, I'm going to be able to play," Leonard told reporters after playing 38 minutes, scoring 22 points and 15 rebounds.

The Spurs high-scoring forward injured his right knee at some point early in the game, then hurt his left ankle when he landed on James Harden's foot late in the third quarter.

He was visibly affected by the ankle injury, and head coach Gregg Popovich opted to sit him for the critical final series of regulation and all of overtime.

Leonard said his ankle was the injury that sidelined him. 

"It's a little sore, but I mean, my team-mates did a good job of closing out that game with me not being able to go that last stretch," he said.

Popovich did not address the question of Leonard's availability for Thursday. He said Leonard wanted to play late in game five, but it was clear he needed to come out.