Rod Stewart's troubled son, 45, is knocked out within FIFTEEN SECONDS by opponent 18 years his junior in nightmare boxing debut

Rod Stewart's success needs no introduction but one of his children encountered their own type of hit-maker at the weekend.

Music legend Stewart, 80, has eight children and his third-eldest child Sean, 45, has turned to boxing.

Sean, 45, a troubled musician who once said being the firstborn son of rock royalty was a 'curse and a hindrance,' made his professional boxing bow on Saturday as he fought on Misfits Boxing's card against streamer BDave, 27, in Nashville, Tennessee.

However, his debut ended in disastrous fashion as he was knocked out within 15 seconds of the fight actually starting. Unsurprisingly, it's a record KO under the Misfits banner.

As the pair engaged in some close-range action, BDave slipped an overhand combination from Stewart before landing an overhand right of his own.

The shot landed flush on Stewart's jaw, who bizarrely then dropped his guard.

And as he backpedalled with both arms down, BDave threw another overhand right that saw Stewart collapse on to the canvas.

Stewart laid motionless on his back as the referee waved the fight, which was scheduled to be three rounds of three minutes, off immediately.

As BDave celebrated, Stewart's corner went over to check the well-being of their fallen boxer.

Stewart, who is 18 years BDave's senior, was branded a 'gym warrior' on commentary by Ben 'The Bane' Davis, and reportedly told Misfits he had been training since the age of six.

His famous father Rod was performing in London so couldn't be present for the ringside defeat.

Despite not being there, his celebrity was often mentioned with Misfits organisers referring to Sean throughout the week as 'Rod Stewart's Son'.

In late February Sean voluntarily checked into rehab after his famous family staged an intervention. 

He spent time at the $80,000-a-month Cliffside Malibu rehabilitation facility, where his close friend Scott Disick once sought treatment.

It came months after he split from his wife Jody Weintraub and started dating Charlie Sheen's ex, Julia Stambler.

'Sean is in rehab for addiction,' an insider told DailyMail.com at the time. 'He's had a long history of substance abuse, and he decided to get help when he saw that he was falling off the deep end again.

'There was a family intervention because they were worried. They are all able to see when Sean is sober and when he is not.'

The source added that Rod was proud of his son for acknowledging that he needed help and checking himself in without being forced.

'In the end, Sean voluntarily checked in to save himself,' the person shared. 'Rod is proud of him for getting help. He is expected to do a 90 day stay, which is the norm.'

The pricey facility features views of the Pacific Ocean, plus an outdoor pool and a gym.

Patients receive treatment while enjoying an organic, chef-provided menu, and turndown service in the rooms. Yoga, walks, equine therapy, acupuncture and group counseling are also offered.

Sean has spoken openly about his addiction battle in the past, revealing he was 'around 13' and a student at Beverly Hills High School when he first started drinking. He later moved on to harder drugs including ecstasy and heroin.

'I would go to parties at that age and drink and smoke cannabis and cigarettes,' he told the Mail in 2012. 'It was very easy for me to get drugs. I would just walk into a party and someone would hand them to me. I hardly ever paid for them.'

He confessed, 'First, I got really badly into Ecstasy. Then I started on the prescription pills like Vicodin, and then cocaine. And finally I got into heroin.'

In January Sean and his girlfriend Julia were pictured on a $150 million super yacht with the Stewart clan in celebration of Rod's 80th birthday.