But to fans, and increasingly to sports entrepreneurs, MMA is a fast-growing global enterprise and nowhere more so than in Brazil, the world's sixth-largest economy and home to three of its seven world champions.
"Brazil is far and away the most vibrant market in every one of the developments; tickets, TV ratings, merchandising, digital, even mobile business, and it is one of our fastest growing social media markets in the world," said Marshall Zelaznik, Managing Director of International Development for the Ultimate Fighting Championship (UFC), the best-known of the sport's governing bodies.
Brazil has gone from being MMA's fifth-biggest market to the third-biggest, behind the United States and Canada, in less than two years, Zelaznik said.
"Brazil has more UFC fans than any other country in the world," he added. "We have over 20 million people watching a televised event at midnight. Companies are interested and they realize there is big consumer demand. I can tell you that there is not a meeting that goes by here at the UFC where Brazil is not discussed."
The success of the sport is no great surprise, given its origins here. An amalgam of everything from judo to wrestling to Thai boxing, some of the MMA's earliest and most successful exponents were experts in Brazilian jiu-jitsu, a self-defense martial art based on locks and choke holds.
The Gracie family of Rio de Janeiro helped popularize the sport and were among the first to compete in the hybrid bouts among proponents of the different disciplines.
What was then known as "Vale Tudo" ("Anything Goes") has soared in popularity in recent years thanks to the UFC. As in boxing, several organizations vie to control the sport but the UFC franchise is the biggest. It has sanitized and regulated a sport that was - and remains violent - and also helped monetize it.
In Brazil, MMA is now considered a serious rival to volleyball and motor racing as the country's most popular sport behind soccer.
"It has been big for a while but the growth has been faster lately because of the number of successful Brazilians," said Fabricio Hendrix, who runs www.mmamagazine.com.br, a Portuguese-language Web site for MMA fans.
"It's also more legitimate now. Fights used to be held in gyms and more often than not they ended in a bloodbath. It wasn't properly organized, there wasn't sponsorship, no gloves, no nothing. But all that has changed."
MMA is now unquestionably mainstream and big business.
Anderson Silva was last year named Sportsman of the Year by GQ Brasil. Another fighter, Minotauro, appeared in Brazil's version of Dancing with the Stars.
Its popularity, particularly in urban areas and among the young adult demographic, has attracted large television audiences and not just on open broadcast channels. The number of people subscribing to the Combat channel has gone from 13,000 in 2006 to 150,000, according to Fernando Ferreira, president of Pluri, a sports consulting firm.
That, in turn, has wooed big-name sponsors such as Procter and Gamble, Unilever, Ford Motor Co., and Volkswagen.
Gillette, which sponsors fighter Vitor Belfort and The Ultimate Fighter reality show, said its name recognition has tripled since beginning their campaign in March. Their latest ad for razor blades featuring seven UFC fighters has been watched more than 16 million times on YouTube in just two weeks.
The man who runs the UFC's licensing arm in Brazil said when they began selling products in April 2011 he estimated they might take in $80 million (£51.54m) in the first year. In fact, the total turned out to be closer to $180 million and that number is expected to rise another 30 percent this year and could double in 2013, especially if more fights are held in Brazil.
"We started last year from scratch and today we have close to 500 products," said Marcos Macedo, director of Exim Licensing. "The kind of growth is phenomenal, for any industry.
The business side is more important than the sport itself because so many people who don't fight are buying products."
That growth seems set to continue -- with a big spike before and after this weekend's Las Vegas showdown between Silva and Chael Sonnen, who hails from the United States.
It is a hotly anticipated encounter, one Sonnen called "the biggest fight in the history of combat."
Silva won the first meeting between the two in 2010 and the animosity between them is reminiscent of the undisguised loathing that characterized the Muhammad Ali-Joe Frazier rivalry 40 years ago.
Record numbers of Brazilians are expected to tune in. And everything suggests they won't be tuning out any time soon.
"One of the things we believe is that we will see 40 per cent growth year-on-year in terms of revenue," said Zelaznik, adding that they hope to host between five and 10 fights in Brazil next year. "And we are bullish because we are only a year and a half into this. The sky is the limit."