The World Chess Championship begins in London on Friday between reigning champion Magnus Carlsen and U.S. challenger Fabiano Caruana. They'll contest twelve matches spread over a three-week period to decide the 2018 winner.

There's over $1 million dollars in prize money on offer, with this match being billed as the toughest to call in years, given how evenly matched the two player's rankings are.

"I want the games to be long and not so much decided by home preparation. It's all about a battle of minds on the board, which is really what I find most exciting. I think this is what Fabiano also finds the most exciting, since he is not the kind of player who relies on home preparation." Carlsen told CNBC on the eve of the opening match.

This head-to-head battle of human intelligence is the Norwegian's preferred form of competition and, despite advances in A.I. technology, he wouldn't want to see a computer entered into the Chess World Championship.

"Computers are better than humans now and that's not going to change," Carlsen said. "I enjoy playing the best, but only as long as it's a human. I enjoy the struggle of playing human players. To me playing a computer is far less interesting and not something I would do in an official tournament or match.'

Carlsen has been the champion since 2010, winning the title three-times in that period, but said in the pre-match conference that his form would need to "step up" if he was to win.

Should 26-year-old Caruana win, he'll be the first American since Bobby Fischer in the mid-1970's to hold the title. Despite the history and the quality of his opponent, Caruana insisted he was looking forward to the challenge.

"His standards are very high, he's still having good results, just maybe not as good as he'd hoped," the Italian-American told CNBC at the launch of the event. "It's like boxing, you have two guys who are slugging it out for a very long time and I think it'll go down to the wire, which is another good reason to tune in." he added.

Chess has 600 million fans worldwide and its promoters claim that makes it the most participated sport in the world.

The newly elected president of chess's governing body FIDE, Arkady Dvorkovich, wants to increase prize-money for future tournaments and ensure the women's game has equal stature. Currently, total prizes on offer for women is roughly a quarter of what the men make.

The 2016 world championship took place in New York and attracted a host of famous names to watch including Bill Gates, Mark Zuckerburg and Jay-Z. A further ten million people followed the match online and that number is predicted to increase this time around.