NASCAR Hall of Famer Tony Stewart has been involved in a terrifying wreck in a NHRA Drag Racing event on Sunday.

Stewart and fellow racer Doug Kalitta were both able to exit their cars under their own power, with the former admitting later that he remembers absolutely nothing of the collision.

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The wreck appeared to be caused by Kalitta's left-front wheel failing as he crossed the finish line, sending him drifting left across into Stewart's car and flipping it briefly onto its side.

For his part, Kalitta called the wreck 'probably the worst' in his long drag racing career, after being released by NHRA Chief Medical Officer Dr. Phil Surface.

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Steward admits blacking out during drag wreck

Stewart, speaking after his own medical checkup, admitted: "I don't have a damn clue, honestly. I don't remember any of it. The first thing I remember, they're waking me up here. Not sure what happened. It appears to be pretty massive.

"I'm as curious as everybody else is to what happened. I just know that we're not where we're supposed to be at the end of a run here. So, just confused.

"I got one hell of a headache and banged my left hand up. But I've been through sprint car crashes way worse than this, I'm pretty sure. We're good. We're good. We're fine. I promise we're fine."

Kalitta added: "It was just unfortunate, really. It just happened so quick that there was nothing I could really do. So just glad we're going to [the semifinals]. We'll drag our other car out and see if we can keep this thing going here, but fortunately Tony and I are good. So that's really the main thing.”

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