At a Gobi Desert encampment, Marco Polo challenged the First Doctor to a game of chess, having just beaten Ian Chesterton. The Doctor won the match after just 26 moves.
Weeks later, while encamped near Su-Chow, the Doctor challenged Marco to a second game of chess. This time, Marco won on the 35th move, after the Doctor threw away an easy win on the 30th. After the match, the Doctor congratulated Marco, insisting upon a rematch the next evening at the Su-Chow way-station. Marco corrected him, stating that their next stop would not be for ten days, in Kan-Chow. (PROSE: Marco Polo)