WHEN the Floyd Mayweather-Conor McGregor megafight was officially announced, every boxer and mixed martial artist with a modicum of business savvy started campaigning to be on the undercard.

You can’t put a price on the level of exposure the opportunity will provide, so everyone wanted to be involved.

Roy Jones Jr and Anderson Silva talked about a crossover bout. Adrien Broner discussed fighting Nate Diaz. UFC heavyweight champion Stipe Miocic challenged Anthony Joshua.

Dillon Danis-Amir Khan, Cub Swanson-Paulie Malignaggi, Cris “Cyborg” Justino-Cecilia Braekhus — the list was never-ending.

But three weeks out from the night at T-Mobile Arena in Las Vegas the list of bouts is starting to come together. And as expected there’s no other MMA v boxing fights — and each clash mooted so far features a man that’s already signed to Mayweather’s promotional company.

Gervonta Davis is likely to face Roman Martinez. Baltimore-born Davis has become one of the biggest stars in boxing after a meteoric rise in the past 18 months.

Still just 22, the fast-talking super featherweight champ stunned Jose Pedraza in Brooklyn in January, before following that with a knockout of Liam Walsh.

The heavy-handed star, dubbed by some as “Mini Mike Tyson”, is now 18-0 with 17 knockouts, and has the whole sport talking.

Davis, who is a part of Mayweather Promotions, always seemed set to appear on the undercard for what will be the richest fight in history.

However, his choice of opponent may rankle with some.

Martinez is a former super featherweight champ himself — but hasn’t won a fight since beating Orlando Salido in April, 2015.

The 34-year-old then drew a rematch with the veteran Mexican, before a brutal fifth-round knockout to dazzling Vasyl Lomachenko.

But that fight was last June — during which time Davis has won a world title and defended it.

Davis will be the heavy favourite for the fight, and it will likely serve as a tune-up to allow fellow American Tevin Farmer time to recover from a hand injury.

Shawn Porter is expected to face Thomas Dulorme.

Porter is coming off a stoppage win against Berto in April this year while Dulorme — who is part of the Mayweather stable — last featured on the undercard of the James DeGale-Badou Jack fight in Brooklyn where he defeated Brian Jones.

Swedish super middleweight champ Jack will also fight, although his opponent remains unknown. Jack was in talks to fight Nathan Cleverly — but the WBA have ordered the Welshman to take his mandatory defence.

British Commonwealth Games gold medallist Savannah Marshall will also make her debut on the bill.

— with The Sun