San Antonio Spurs coach Gregg Popovich said Victor Wembanyama's absence from Saturday's defeat to the Dallas Mavericks was precautionary after the rookie was injured in a "freak" incident involving a ballboy.

Wembanyama did not play after rolling his right ankle during his pre-game warm-up, sustaining the injury when he stepped on a ballboy's foot following a driving layup.

The number one draft pick's absence was keenly felt as the Spurs fell to 4-24 with a crushing 144-119 defeat, Luka Doncic scoring 39 points in a triple-double within just three quarters for the Mavs.

With Wembanyama having missed Tuesday's defeat to the Milwaukee Bucks after experiencing pain in the same ankle, Popovich said the Spurs couldn't afford to take any risks, much to the 19-year-old's annoyance. 

"If it was a playoff game, I probably would've played him," Popovich said after the defeat. 

"He's not happy about it, but I would rather err on the conservative side since it's the same ankle that you just got a time limitation on. 

"But it was just a freak, freak accident before the game. You see it on the film, and you can't believe it."

Wembanyama is averaging 18.5 points, 10.7 rebounds and three blocks for the Spurs in his maiden campaign, with Saturday's game just the third he has missed.

For the Mavs, Doncic added 12 rebounds and 10 assists to his 39 points before departing near the end of the third quarter, recording his 36th 30-point triple-double, one shy of the league's record holder LeBron James.

It was his sixth triple-double of the season, while he is now just 11 points shy of 10,000 for his NBA career, a figure he will be confident of bringing up against the Phoenix Suns on Christmas Day.

More importantly, the result ended a three-game losing streak for a Dallas side still deprived of Kyrie Irving due to a heel injury, leading Doncic to praise the team's togetherness. 

"We still have some injuries, so we've got to still keep it together," he said. "Everybody's got to stay together and have a next-man-up mentality."