The Oklahoma City Thunder’s early season forecast just became a little foggy.

On Wednesday, two-time scoring champ and 2017 MVP Russell Westbrook underwent arthroscopic surgery on his right knee, which will keep him out of all pre-season activity and could force him to miss a few regular season games.

Multiple outlets are reporting that he will be re-evaluated in four weeks. The Thunder open their season on Oct. 16 against former teammate Kevin Durant and the Golden State Warriors.

Westbrook has had three previous procedures on a knee that he originally injured in the 2013 playoffs when he ran into Patrick Beverley of the Houston Rockets. He tore his meniscus and had to undergo three surgeries in a span of nine months. He hasn’t had any since and Wednesday’s scope was deemed pre-emptive “maintenance” after he experienced stiffness in the affected joint.

Westbrook, 29, led all players in assists in 2017-18 with 10.3 per game and added 25.4 points and 1.8 steals.