Darren Till and Aaron Chalmers will go head-to-head this weekend in the Bare Knuckle Fighting Championship.
For Till, it is a debut for the promotion at their BKFC90 event in Birmingham on Saturday May 30.
But what are the rules of bare knuckle fighting? What weight class will Till and Chalmers meet in, and who are the champions? Here's everything you need to know.
What are the rules in BKFC, bare knuckle fighting?
The key difference point of this form of combat is that the fighters do not wear gloves.
However, they are allowed to wrap and tape the wrist, thumb and mid-hand -- but the knuckle must be left bare.
The only strike allowed is a punch with a closed fist. That means elbows, kicks or anything else are outlawed.
In a clinch, fighters can use their spare hand to punch out. If a clinch lasts three seconds, the referee can break the fighters up.
If a fighter is knocked down, he has 10 seconds to get back to his feet, just like traditional boxing. Fighters cannot punch a downed opponent (this is punishable by disqualification). Fighters must report to a neutral corner if their opponent is knocked down.
Fighters must wear a groin protector with a cup, a mouthpiece, boxing trunks, and boxing or wrestling shoes.
How many rounds? How long are the rounds?
Fights are five rounds of two minutes each.
The ring isn't like a traditional boxing ring...
The BKFC promotion uses a unique circular four-rope ring which aims to encourage fast, exciting fights, called the 'Squared Circle.'
Fights begin when the referee asks fighters to 'toe the line.' This means to stand on their designated lines, which are three feet apart on the ring canvas. When the referee asks them to 'knuckle up,' the fight begins. This pays homage to the Broughton Rules which governed bare knuckle fights in the 19th century.
How does blood impact a fight?
If a fighter's vision is obscured by blood, the referee can call a time-out to give a cut-man 30 seconds to quell the bleeding. If the bleeding cannot be stopped and continues to hamper a fighter's vision, the referee can stop the fight and award victory to the opponent.
What weight class will Till and Chalmers fight in?
Till and Chalmers will meet at light-heavyweight, which is 185 pounds.
This is the equivalent to the UFC's middleweight division. Till fought for the title in the UFC at welterweight (170lbs) but notoriously struggled with the weight cut.
What are Darren Till's credentials?
Till went unbeaten in his first 18 MMA fights, most notably beating Stephen 'Wonderboy' Thompson at home in Liverpool, to become Britain's big UFC hope.
However, he lost his sole title shot against welterweight champion Tyron Woodley. That began a spiral of losing six out his last seven UFC fights, including a knockout against Jorge Masvidal.
He won a boxing exhibition after leaving the UFC, then won two Misfits fights, including against fellow ex-UFC fighter Darren Stewart.
Impressively Till knocked out former UFC champion Luke Rockhold last year, in his only match under traditional pro boxing rules.
A new journey now awaits without gloves.
What are Aaron Chalmers' credentials?
Chalmers became known for his role on 'Geordie Shore' but has since built a CV in fight sports, crossing into multiple disciplines.
He began in MMA, fighting notably in the Bellator promotion. Chalmers won five of his seven fights.
Chalmers won his only professional boxing match but lost his sole appearance in the Misfits promotion, against Idris Virgo.
Remarkably, he shared a ring under exhibition rules with Floyd Mayweather in 2023. Chalmers boxed three exhibitions in total.
Most recently he has fought in BKFC, winning both fights. Last year he knocked out Jack Fincham of 'Love Island' fame.
Who are the bare knuckle champions?
At light-heavyweight, where Till and Chalmers will meet, the champion is Lorenzo Hunt, 43, who has won 13 of 15 fights. Hunt also tops BKFC's pound-for-pound rankings.
Andre Arlovski and Alessio Sakara are the champions at heavyweight and cruiserweight respectively. John Dodson holds flyweight gold. Notably, they are all UFC veterans.
Jamel Herring, the ex-boxing world champion, holds the bantamweight title.