Heartbreaking moment Kyle Busch calls for medical assistance in his car during NASCAR race just days before his shock death at 41

This is the eerie moment tragic racing star Kyle Busch radioed for medical assistance from his car in the middle of one of his final NASCAR races just days before his death.

Busch died at the age of just 41 on Thursday, and no cause of death has yet been revealed for the man who has won more NASCAR races than anyone else in history.

Soon after his death was announced, a clip from one of his final ever races went viral, at Watkins Glen in upstate New York on May 10.

With 38 laps to go in the NASCAR Cup Series game, Busch told his team over the radio: 'Can somebody try to find Bill Heisel? He's the kindred doctor guy.

'Tell him I need him after the race, please.'

He was then asked whether he needed the doctor at his car or his bus, to which he replied: 'Uh, bus. I'm going to need a shot.'

According to the TV broadcast, Busch had been struggling with a sinus cold that was exacerbated by the intense G-forces and elevation changes at the New York road course.

Busch went on to finish that race in eighth place, and five days later on May 15 he spoke to the media to give further details about his ongoing illness.

'You can still hear it... I'm still not great,' he said. 'The cough was pretty substantial last week.'

Busch went on to claim his record fifth NASCAR Craftsman Truck Series trophy that day, despite clearly still struggling with illness.

Following his death, which came just six days after the victory, a heartbreaking clip of Busch's post-race interview resurfaced.

After earning his 69th career Trucks Series race win with the triumph at Dover, Busch was asked how many races he wanted to win in his career before he stops racing.

'You take whatever you can get, man,' Busch said. 'You never know when the last one is going to be, so cherish them all - trust me.'

It remains unclear whether his sinus issues and cough were related to the cause of his death.

In the wake of his shock passing, tributes have flooded in from NASCAR and across the racing world.

'Our entire NASCAR family is heartbroken by the loss of Kyle Busch,' NASCAR shared in a statement on behalf of Busch's family and his team, Richard Childress Racing.

'A future Hall of Famer, Kyle was a rare talent, one who comes along once in a generation. He was fierce, he was passionate, he was immensely skilled and he cared deeply about the sport and fans.

'Throughout a career that spanned more than two decades, Kyle set records in national series wins, won championships at NASCAR's highest level and fostered the next generation of drivers as an owner in the Truck Series.

'His sharp wit and competitive spirit sparked a deep emotional connection with race fans of every age, creating the proud and loyal "Rowdy Nation".

'Our thoughts are with Samantha, Brexton and Lennix, Kyle and Samantha's parents, Kurt and all of Kyle's family, Richard and Judy Childress, everyone at Richard Childress Racing, his teammates, friends and fans.

'NASCAR lost a giant of the sport today, far too soon. During this incredibly difficult time, we ask everyone to respect the family's privacy and continue to keep them in your thoughts and prayers.'