and at the san francisco gym where zuckerberg trains, his followers think he ll run rings round his rival. he s got some skill for a beginner. he s got some skill. in recent years, mixed martial arts has been one of the world s fastest growing sports. and its popular here, too. this is a gym near belfast where there s a bit of scepticism about a silicon valley scuffle. it s not a good way to settle grudges. you know, it s a sport at the end of the day. i think firstly, it s probablyjust a big publicity stunt, which is working really well. but if musk meets mark, will it be no holds barred, or will there be rules? eye gouging and biting and smalljoint manipulation, all that kind of stuff is illegal. groin strikes, of course. but it s all martial arts put together, so it s grappling, it sjujitsu, it s muay thai striking, it s boxing, karate, pretty much everything.