Kawhi Leonard will not play for the San Antonio Spurs in Game 6 of their Western Conference semifinal series against the Houston Rockets after suffering an ankle injury in Game 5, head coach Gregg Popovich announced on Thursday evening.

Leonard rolled his ankle in the third quarter of Game 5 when he inadvertently stepped on the foot of Rockets guard James Harden:

Leonard remained in the game, and played in both the third and fourth quarters, but was hobbled by the injury. He sat out the final possession of regulation and all of overtime. Manu Ginobili and Danny Green led the Spurs to victory in Leonard’s absence.

Jonathon Simmons will replace Leonard in the Game 6 starting lineup as the Spurs look to close out the series in Houston.

Leonard, speaking after the Game 5 win, was convinced he would play, despite admitting the ankle was sore.

The team was always slightly less optimistic, however. Popovich listed him as questionable. “I want to take as much time as possible and see what he feels like,” he said earlier on Thursday.

Leonard, according to Popovich, wanted to play, but it was Popovich’s decision to hold his star player out:

Had the Spurs dropped Game 5 at home, the decision-making process likely would have been far different, and a limited Leonard probably would have been allowed to play. But with Game 6 not a must-win for the Spurs, and with two days off in between Thursday’s game and a potential Game 7 at home on Sunday, the safe move was to go without Leonard.

If the Spurs had activated Leonard on Thursday, the nightmare scenario — an ineffective Leonard and a re-aggravation of the injury — would have been in play. That not only would have ruined Leonard’s Game 6, but possibly could have ruled him out of Game 7 as well. By keeping him off the court, the worst-case scenario is that the Spurs head back home as a favorite in Game 7, and with Leonard likely healthy enough to return to the lineup.

Simmons, Leonard’s replacement, not only stepped up in the second half of Game 5, but has contributed all series. The second-year guard from Houston is averaging 12.2 points per game over the five contests, and has been effective on the defensive end as well. He has guarded Harden — and guarded him well — with Leonard out of the game.

The Spurs were actually 7-1 without Leonard during the regular season, but his absence is a massive one. San Antonio’s depth was already diminished by the loss of Tony Parker to a torn quad tendon in Game 2. Without Leonard, San Antonio will be missing its offensive catalyst and its defensive answer for Harden. With Leonard ruled out, Las Vegas bookmakers have bumped Houston up to a 9-point favorite in Thursday’s game, which tips off at 8 p.m. ET.