Chess master

A chess master was someone who was particularly adept at playing the game of chess.

In 2266, James T. Kirk introduced Spock to Charlie Evans as "our chess master". 

In 2269, Kirk decided to attempt to obtain the ryetalyn that Flint had hidden behind a door, saying "let's not disappoint the chess master". This referred to Flint himself, who seemed to be playing games with the landing party.