Shai Gilgeous-Alexander scored the winning points deep into double overtime as the Oklahoma City Thunder started their NBA title defence with a 125-124 victory over the Houston Rockets.

Last season's MVP scored 35 points, including two from the free-throw line with just 2.3 seconds remaining in second overtime, to get the champions off to a positive start.

Houston's Alperun Sengun top-scored with 39 and also hit a career-high five three-pointers.

But Chet Holmgren, who scored 28 points for the Thunder, played a major role alongside match-winner Gilgeous-Alexander.

"Grit, determination and defence," Gilgeous-Alexander said of their performance.

"We know that when we do it (on defence) we give ourselves a chance no matter what's going on - makes, misses, good luck or bad luck. We did enough defence to get the win. We're pretty rusty, but it's a good start."

Prior to the game, Oklahoma's championship banner was raised at their home court, while the players were presented with championship rings.

The Thunder beat the Indiana Pacers in last season's best-of-seven NBA Finals. It was their first title since the franchise moved in 2008 to Oklahoma City from Seattle, who had won the 1979 crown.

The Pacers will have the chance to secure some early revenge on Friday when they host Oklahoma, while the Rockets return to action on the same day at the Detroit Pistons.

Elsewhere, a huge effort of 43 points, 12 rebounds and nine assists from Luka Doncic was not enough to prevent his new team the Los Angeles Lakers from falling to a 119-109 defeat against the Golden State Warriors.

Jimmy Butler picked up 31 points and Stephen Curry added 23 for the visiting Warriors.

The Lakers were without the NBA's all-time leading scorer LeBron James as he recovers from sciatica.