At the Frankfurt Chess Classics tournament, the two rivals will be joined by Indian Vishwanathan Anand, 29, the world second-ranked player and Russian Vladimir Kramnik, 24, the number three.

In 1985, when he was 22 years old, Kasparov became the 13th and youngest world champion in the history of chess, beating archrival Anatoly Karpov in Moscow. Despite rifts in the world game Kasparov is still universally acclaimed as the best player in the world.

Their last encounter between the two K's took place in Spain in 1996.

His epic struggles with former champion Karpov also became symbols of the Jewish-Armenian, Kasparov supporting the reformist Mikhail Gorbachev, and subsequently Russian president Boris Yeltsin, while the ultra-conservative Russian Karpov remained a model communist.

For 18 years the two champions played out the greatestrivalry in the history of chess, disputing five world championship finals.

The aggregate score favours Kasparov, 36, who has chalked up 28 victories against 20 losses with 119 games drawn.

In February 1993, Kasparov split from the International Chess Federation (FIDE) and created the Professional Chess Association, through which he won the world championship against Briton Nigel Short.

With his thick-set build, authoritarian demeanor and all-consuming drive to win, Kasparov became a celebrity with nicknames like ``the ogre of Baku'' and ``the hundred-eyed monster who sees everything.''

He was born in 1963, in Baku, capital of the former Soviet Republic of Azerbaijan, the son of a Jewish father and an Armenian mother.

After his battles against Karpov, and feeling he had no human competition left, Kasparov took on the might of IBM computers. He eventually lost to ``Deep Blue'' in 1997.

His latest tussle with new technology sees him taking on all-comers on the internet, courtesy of Microsoft.

Forhis part, Karpov, 48, now commands only ninth place in world rankings, but has remained FIDE world champion since Kasparov's defection.

In the Frankfurt tournament running from today to Friday, Kasparov, Karpov, Anand and Kramnik will play a form of speed chess, with 25 minutes to make their moves.

Last year, Karpov pulled out of a Frankfurt tournament at the last minute, after discovering that Kasparov was taking part.