Game 5 of the World Chess Championship yesterday was postponed until Monday at the request of defending champion Gary Kasparov.

This is the second postponement in the first two weeks of the match. It is, however, an expensive luxury; each player is allowed only three postponements for the whole 24-game match. The postponement also pushes back the scheduled Nov. 10 conclusion of the New York phase of the match, which is to include the first 12 games.

No reason was given for Kasparov's postponement of last night's scheduled game. The usual reasons are fatigue, illness and psychological problems, which usually stem from a lost game. Kasparov has not lost yet; after four games, he leads by a score of 2 1/2 to 1 1/2, with three draws. But he may have been shaken by a close escape in Game 4 Wednesday, when Karpov organized an impressive queenside attack from which Kasparov managed to escape with a draw by perpetual check. Despite his one loss, Karpov has been playing unusually imaginative and enterprising chess, and Kasparov may be more surprised and upset than he has shown.

Game 5 is scheduled to start at 5:30 p.m. Monday with Karpov playing white.