This is the incredible moment a quick-thinking jockey dived in to help his horse after it collapsed mid-race in Australia.

Champion horse Think About It suffered catastrophic internal bleeding during the running of the Sydney Stakes on Saturday.

Jockey Jason Collett was thrown from the sprinter but quickly got to his feet to provide comfort for the distressed horse as it flailed its legs in the air.

In the footage, Collett is seen running to hold the horse's head as the rest of the pack bolts towards the finish line.

Think About It, winner of the 2023 Everest, made a 'miraculous' recovery after 'cheating death' - though trainer Joseph Pride confirmed the horse would be retired.

Mr Pride said he worried the injury could have been the end for the racehorse after it fell during the Sydney Stakes on October 19.

A screen was brought out to block the distressing scene from the view of the packed crowd, which is often a certain sign the horse is about to be euthanized.

'I have seen horses come down like that before, and they don't get back up, unfortunately,' Mr Pride told The Sydney Morning Herald.

'Once they put that screen up, they're not coming out.'

Remarkably, the horse's head popped back up, with Think About It having been helped to its feet.

'I saw his head pop up above the screen. It was amazing. I just thought 'Aahh, what a relief,' Mr Pride added.

The horse was then walked from the track back to his box, where a veterinary assessment revealed the severity of the heart issue.

The owners and trainer made the immediate decision to retire the horse from racing, saying it was an 'easy decision' as it was a 'big bleed'.

'I don't believe in any higher powers but honestly, something happened there,' Pride said.

'I don't know what happened. There is a scientific explanation there but it is beyond me. He shouldn't have got up.'

Soon after they reported that the horse was 'bright and happy', having made a miraculous recovery from the horror fall.

'I am so happy to see him this morning. I can't even believe he doesn't even seem to be sore from the tumble. He rolled over and at speed, they're going about 60km/h.'

Think About It, sired by two-time Cox Plate Champion So You Think, was distressed and Collett said his first instinct was to try and get him back to his feet.

'I'm OK and amazingly the horse has walked back to the stalls,' Collett said.

'They don't do that. I thought he'd broken down but he's bled out.'

Collett's bravery was lauded by racing fans.

'Graphic footage [but] love to hear Think About It will be living life like a King from here on out in retirement,' racing analyst John Wall posted to Twitter/X after the incident.

'But huge respect for Jason Collett in a crazy dangerous situation, trying to comfort the horse without any hesitation.'