World Chess Battle Heads for Tiebreak Endgame

The battle for the world chess crown heads into a four-game tiebreaker on Wednesday, after 12 regular rounds failed to separate reigning champion Magnus Carlsen and his Russian challenger Sergei Karyakin.

After a win apiece and nine draws, the pair head into the chess equivalent of extra time in soccer, beginning a series of four quickfire games in New York at 2pm (1900 GMT).

Unlike the earlier rounds, which lasted an average of six hours, the rapid play rules mean the players have just 25 minutes each, so each game will be over in an hour.

If they are still tied afterwards they will play a series of blitz games, played at the rate of five minutes per player at the start, with three seconds added after each move.

"If there is still no winner, Carlsen and Karyakin will play an Armageddon game in which white has five minutes and black has four, but black only has to draw to win the match," the World Chess Federation said.

The accelerated games leave plenty of opportunity for harried mistakes, and while predictions are difficult, Carlsen -- a king of the blitz format -- remains favourite.

The Norwegian, who turns 26 on Wednesday, has played several blitz tournaments this year, beating U.S. grandmaster Hikaru Nakamura in one in October.

But he has occasionally shown flashes of losing his cool, as when he slammed the door of the press room after defeat in the eighth round, earning a fine of five percent of his prize money. 

- 'Capable of upset' -

Karyakin, a child prodigy who became the youngest ever chess grandmaster at the age of 12, has known Carlsen for years and has little to lose, with no-one even expecting him to reach the final.

"Sergei has impressed everyone with his tenacity these last few weeks so he is perfectly capable of pulling an upset," said So, who traveled to New York from Minnesota to watch the clash.

Much has been made of the clash as a reprise of the great Cold War chess battles of the 1970s, but Karyakin, who is from Crimea and supported Russia's 2014 annexation of the peninsula, has played down political overtones.

But he knows that a hero's welcome will await him in Russia -- where chess was elevated to the status of national institution in the Soviet era -- if he wins the crown.

The last Russian to claim the title was Vladimir Kramnik in 2007. 

In a sign of the final's significance to Moscow, President Vladimir Putin's spokesman Dimitry Peskov was in New York to see the start of the head-to-head.

As well as the title, the winner will also take home 600,000 euros ($637,000), while the loser will walk away with a consolation prize of 400,000 euros.