There comes a stage in every budding romance when a God-fearing Englishman must stiffen the sinews, summon up deep reserves of courage, and introduce his new girlfriend to that precious group of people who monopolise the lion's share of his waking hours: his workmates. For Alex Reid, the muscular former Hollyoaks star who has become embroiled in the real-life soap-opera of a relationship with recently-divorced headline magnet that is Katie Price, this always-tricky process will have represented a particularly daunting prospect.

Why so? Well, to earn a crust, Mr Reid has lately pursued two distinct career paths. One as a leading light of the adult entertainment industry, headlining low-budget British porn flicks like Killer Bitch; the other as a fearsome professional in the fast-growing combat sport of Mixed Martial Arts [MMA]. Cannily, he chose the latter arena for Price's first outing before professional colleagues, taking the former glamour model and reality TV star – who has "rebranded" herself after for years being known as Jordan – to an event called the Extreme Brawl Fighting Championship.

As romantic venues go, their ringside seats floodlit at Heathrow's Raddison hotel may seem slightly wanting. But anyone familiar with sporting phenomenon that is MMA will tell you that Mr Reid has in fact now elevated his new squeeze to the very trendiest of sporting circles. Football WAGs, who burst into the public consciousness during the 2006 World Cup, are now so sullied in the public imagination that any sprightly female with so much as an ounce of commonsense must surely now aspire to the more fashionable milieu of the cage-fighter's octagon.

Download the new Independent Premium app Sharing the full story, not just the headlines

The upstart sport may not offer the financial rewards of its mainstream rival (though it has certainly made millionaires of British stars like Michael Bisping) but for straightforward street-credibility, it leaves the pie-and-chips world of the football terraces trailing in its wake. In America, MMA has morphed into a billion-dollar industry, with the UFC, the Premier League of the sport, turning a profit of more than $200m [£130m] last year. Ringside seats at top events change hands for up to $50,000 a pair. More than a million pay-per-view punters pay $45 to watch each event.

The appeal is part aesthetic (fans count MMA as the most thrilling and varied of all combat sports) and part show business: the front rows at UFC events in Vegas, the sport's spiritual home, contain a bejewelled mixture of Hollywood stars, and "legitimate" businessmen of the sort that, in a previous era, glamorised professional boxing. The atmosphere, meanwhile, can veer between enthralling and bloodthirsty. Educated fans, who despite their beefy appearance tend to be from solidly white-collar stock, appreciate the subtleties of a sport that can marry the best of ju-jitsu, boxing, Greco-Roman wrestling and kickboxing.

Fights can be won and lost in myriad fashions, which adds to the complex allure – even if a fair proportion of punters, particularly in the cheaper seats, turn up to witness the ground-and-pound and big knockouts that in MMA's early days a decade back saw it dismissed as a human version of cockfighting.

On Monday, Price was perhaps brought face-to-face with the ugly side of the sport when "The Reidenator," as her new boyfriend is known, became involved in an ugly ringside brawl. Witnesses claim he was punched in the face by associates of the gypsy fighter Tony Giles.

"One of them fancied his chances and wanted to prove himself by asking Alex to step outside," the event's promoter Andy Jardine told reporters. "Alex said, 'I'm not being funny but ... I've fought some of the best in the world.' He didn't like that answer and the fight started there." The kerfuffle was eventually calmed by security.

Despite the setback, Reid and Price are surely now the Posh and Becks of their sport, slotting neatly on to the top table of British cage-fighting's foremost celebrity couples. Their peers include star welterweight Dan "the Outlaw" Hardy and his partner Elizabeth Holloway, and Liverpudlian lightweight Terry Etim, whose girlfriend Jodi Tennant turns out to be first cousin of the notorious football WAG Danielle Lloyd.

Both girls recently offered The Independent useful advice to advice to the new WAG on the block – including the thorny matter of watching the man you love being beaten to a bloody pulp before a paying audience. "People often ask what it's like being a fighter's girlfriend, if you get stressed out, or concerned, or lose sleep," admitted Ms Holloway. "Well of course you do. But you just have to accept that they are doing something they love. When Dan has to take time off, and doesn't get to the gym and spar, he's a lot harder to deal with."

Ms Tennant, for her part, suggested that Ms Price's greatest struggle may in future involve tempering her famously extravagant libido, noting that bedroom recreation is strictly forbidden in the week that precedes a fight. "That's an absolute rule," she said.