The Houston Rockets are unsure if star guard Russell Westbrook will be available for the start of the NBA playoffs.

Westbrook sat out Wednesday's 108-104 loss to the Indiana Pacers after an MRI confirmed a strained right quadriceps.

The 2017 MVP has already been ruled out of Friday's final seeding game against the Philadelphia 76ers and Rockets head coach Mike D'Antoni is unsure when Westbrook will return.

"We'll see how it responds and everything, but we all hope," D'Antoni. "We'll just see next week. I don't know right now."

Westbrook, who posted 20 points, six assists and five rebounds in the Rockets' defeat against the San Antonio Spurs on Tuesday, had previously felt discomfort in his right quad.

The nine-time All-Star sat out back-to-back games after feeling soreness during a loss to the Portland Trail Blazers on August 4.

"I don't think he aggravated it [against the Spurs]," D'Antoni said. "During the game and after the game, he was fine. He woke up the next day and was sore, so they're checking it out to make sure it can respond to treatment.

"We don't know 100 per cent right now, but he's definitely going to be out Friday and then we'll see."

A blockbuster acquisition from the Oklahoma City Thunder, Westbrook has been averaging 27.2 points, 7.9 rebounds and 7.0 assists per game.

The Rockets – fourth in the Western Conference – are eyeing their third NBA championship and first since 1995.