Morphettville trainer Darryl Carrison has opened up on his split-second decision that helped prevent a disaster in the first race at the Quorn Cup on the weekend.

A horse that was scratched from the race broke free from an attendant at the gates and started galloping the wrong way on the track towards the oncoming field.

WATCH THE VIDEO ABOVE: Hero horse trainer prevents on-track disaster.

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Carrison noticed the runaway horse and made the quick call to jump on the track in an attempt to divert it.

He can be seen waving his jacket, which helped the horse avoid the others.

“I was just thinking, God, it’s got to get off the track. This will be a disaster if it doesn’t,” Carrison told 7NEWS.

“I pulled my jumper off to make myself look a bit bigger. I started waving it through the air because it was going quite quick.

“It had its head down and it was seeing straight through me.”

Stunned fans watched on as the horse eventually veered away from the oncoming group.

Jockeys in the race had also attempted to slow down their mounts to avoid the potentially catastrophic situation.

No one injured during the chaos, but the race was declared void.

The runaway horse was also returned to the mounting enclosure unharmed.

Quorn jockey club president Dean Montogmerie praised Carrison for his quick-thinking actions.

“He’s a great horseman, so he’s had the confidence, obviously, and the willingness to divert a what could have been a fatal incident,” he told 7NEWS.

“But it was amazing. We just could not believe it.”