Kasparov in 16-game tournament against his former pupil Kramnik

World chess champion Garry Kasparov has begun a 16-game tournament against his former pupil Vladimir Kramnik, which he has described as the greatest challenge to his crown. Kramnik is the world's number two player and was first taught by Kasparov at the age of 11. Correspondents say the contest resembles that in 1985 when Kasparov - then in his early 20s, like Kramnik now - snatched the world chess title from Russia's Anatoly Karpov. The victor in the contest, being held in London, stands to win $2m - though Kramnik said the title was more important to him than any prize money. Kasparov and Kramnik have played together 23 times in serious tournament play, with three victories each and 17 draws. BBC