Oklahoma City Thunder center Bismack Biyombo collapsed in the middle of a game Wednesday night — scaring the hell out of his teammates … and the troubling scene was all captured on video.

It happened during the second quarter of OKC’s tilt against the Trail Blazers in Portland … when Biyombo was trying to lift up some Thunder players as they walked toward the bench for a timeout.

But, as you can see in the game’s broadcast footage, as Biyombo was slapping some hands … he started to sway — before he dropped into some chairs nearby.

The 31-year-old laid on the ground motionless for several seconds … sending his teammates into a panic. Thankfully, however, he was able to get up and walk off the court under his own power — while holding the back of his head.

It’s unclear what exactly went wrong with the NBA veteran … but OKC head coach Mark Daigneault said it looks like he’s avoided a serious ailment.

“He’s fine,” the coach said after the game. “He just fainted, basically. He was in the locker room at halftime laughing and joking.”

Biyombo — who joined the Thunder last month after beginning the season with Memphis — did not play in the rest of the game … although the Thunder still won, 128-120.