Pitted against each other, who'd be the stronger man - Muhammad Ali or Bobby Fischer?

Indeed, the mettle in boxing, as the Greatest would tell you, is in the mind, not brawn. On the surface, chess and boxing seem like odd bedfellows. But really, in the mental skillset needed for either, they are a marriage of equals.

Here, Indian chessboxers spar with their minds during the chess round of the National Chess Boxing Championships in Kolkata.

Chessboxing, a hybrid sport combining the mental workout of chess with the physical challenge of boxing, is popular in Germany, Britain, Russia and France, with Asian countries like China, Iran and India catching up fast.

A chessboxing fight consists of six rounds of chess and five rounds of boxing. The rounds alternate, but begin and end with the silent challenge of the board.

AGENCE FRANCE-PRESSE