The Thunder announced before the game that Westbrook had arthroscopic surgery on his right knee and is out until after the All-Star break, at least 27 games.
Durant scored 14 points in the fourth quarter and finished 14 of 28 from the field. Serge Ibaka had 12 points and nine rebounds for the Thunder, which has won seven straight road games and 11 of 12 overall.
Reggie Jackson started in place of Westbrook but made only four of 19 shots.
In his last game on Christmas, Westbrook didn't look like a player who was in pain, finishing with 14 points, 13 rebounds and 10 assists in a 123-94 rout of the New York Knicks.
"He will be missed," Coach Scott Brooks said before Friday's game. "Obviously, we are a very good team with him, and without him we're still going to be a very good team."
at Sacramento 108, Miami 103 (OT): DeMarcus Cousins had 27 points and 17 rebounds, Rudy Gay scored 26 and the Kings rallied from an early 17-point deficit to beat the Heat, which played without Dwyane Wade, Ray Allen and Chris Andersen.
at Brooklyn 104, Milwaukee 93: Shaun Livingston scored 20 points, Mirza Teletovic came off the bench to add 19 and the Nets rebounded from an embarrassing Christmas Day performance by ending their four-game losing streak.
Toronto 95, at New York 83: Jonas Valanciunas had 16 points and a career-high 18 rebounds, DeMar DeRozan scored 25 points, and the Raptors rallied by outscoring the Knicks in the fourth quarter, 29-12.