How safe is bare-knuckle boxing as it struggles for mainstream appeal?

“One punch can change your life. But I love this sport.”

Naked boxer Liam Rees realizes the dangers when he steps on the canvas.

The Welshman juggles his day job as a carpenter with the demands of a sport so brutal that it has remained in the shadows of combat sports for much of its existence.

Collapsed into a chair moments after losing his lightweight world title at the Valley Sport Arena, Cardiff, the Swansea native’s wife Emma is sweetly pleading with her bloodied partner to give up the sport.

“No more now, dear,” she says.

But nothing can replace the hype for him.

“You have a lot of adrenaline pumping through your body in that episode,” he told BBC Sport.

“Some people think I’m crazy.”

In sanctioned events, fighters compete toe-to-toe on surfaces half the size of a professional boxing ring — meaning there’s nowhere to hide.

There are more cuts, bruises and knockouts – which is exactly what appeals to some fans.

After overcoming drug abuse issues, the 31-year-old was introduced to the emerging combat sport through a trainer at his boxing gym.

He made his bare-knuckle boxing debut in 2023, becoming a two-time BKB light middleweight world champion.

During camp, Reese trains three times a day, five days a week, neglecting to see his two children on weekdays.

He does not earn enough from this sport to leave his carpentry job. His goal is to leave “a legacy, just to prove to the city that I did something for them.”

Bare knuckles are considered the oldest form of boxing but became associated with unsanctioned fights in wastelands after the introduction of the Marquess of Queensberry rules in 1867, which insisted on the wearing of gloves.

However, in the past decade, licensed events have grown. According to BoxRec data, there were only 21 licensed bouts in 2015. Last year, the number was more than 1,000 bouts in 21 countries.

Rees fights under the banner of Bare Knuckle Boxing Promotions (BKB) – one of two major international promotions that host licensed bouts, along with the US-based Bare Knuckle Fighting Championship (BKFC).

Attendance at BKB venues is capped at 2,000 people, and organization president David Tetrault says tickets are generally sold out.

BKB is broadcast in over 60 countries, and has partnerships with the likes of VICE TV and TalkSport.

Retired world boxing champions Lee Selby, Paulie Malignaggi and James DeGale have all crossed over to bare-knuckle boxing as its popularity grows.

However, Luke Griggs, chief executive of brain injury charity Headway, said he was “deeply concerned” about its rise and “glamourizing the sport that will be taken to the streets”.

In a new film, BBC Sport looks at the realities of a sport that is slowly becoming more popular, and the people at its heart.