Australian Marcos Ambrose has spoken of his horror at being trapped in the middle of the most spectacular high-speed crash in NASCAR this year.

The former V8 Supercar champion was a key figure in the incident in Talladega, Alabama, which saw American Ryan Newman flip end-over-end in a horrifying pile-up from which he was lucky to escape without serious injuries.

Ambrose, who is preparing for this weekend's Dickies 500 at Texas Motor Speedway in Fort Worth, was stunned that Newman was unhurt after watching his car somersault through the air.

"Talladega was great until we had five laps to go and then it all went pear-shaped on me," Ambrose said.

"I'm not sure what happened, but I just feel terrible for the outcome.

"Ryan on his roof and Tony (Stewart) taken out of contention for the championship.

"We were all in line at the top and I thought I was in the safest spot I could be.

"I was helping push Ryan and Tony up through there because I felt those guys were going to go to the front.

"The next thing I know, I was in the back of the 39 car and I don't know what started it - whether I was getting pushed from behind or whether the guys ahead of us checked up.

"Then I'm spinning out backwards and watching Ryan flip through the air as he's chasing me upside down. I had a terrible feeling in my stomach that Ryan was hurt. Thankfully, he got out OK."

Ambrose said one of the problems was restrictor plates which the cars have to use to reduce speeds at the two quickest banked "superspeedway" circuits - Talladega and Daytona.

"That plate racing is a real challenge and you put yourself in such bad positions to try to get to the front. When something goes wrong, you just don't have any time to react," he said.

The pile-up wrecked Ambrose's chances of another high finish and dropped him to 18th on the Sprint Cup points standings, but he said he was optimistic going into this weekend's Dickies 500.

He was running in 11th place and was a potential top-five contender at the fast 1.5-mile oval earlier this year but an engine failure ended his day early.

"We ran well there and it's a good track for me, Ambrose said. We just need to have a good finish. We've had some bad luck recently and we want to end our season on a high note.

"Next season, we hope to win races and be in the top-12, which is ambitious, but realistic since we think we'll finish somewhere around 17th in the points.

"We started off with expectations to at least finish in the top 35 and right now with three races to go we are in the top-20, he said.