Challenger Gary Kasparov resigned Game 22 of the world chess championship today to champion Anatoly Karpov.
Caught in a hopeless position, Kasparov did not resume play in the adjourned game.
The champion now trails by only one point (10 1/2 to 11 1/2), with two games to play.
Karpov needs at least one more win and a draw to tie the match and retain his title. Kasparov becomes the champion if he wins one game or draws both.
Game 23 is scheduled for Thursday although it is Revolution Day, a major Soviet holiday.
Karpov reportedly asked to have the game postponed but was turned down by the match arbiters.
The champion's confident comeback surprised the capacity crowd and grandmasters in Tchaikovsky Hall.
At the end of Tuesday's marathon five-hour session, the champion -- never a favorite with the local Moscow supporters -- was given a prolonged round of applause.
Kasparov, nervous and edgy throughout, stayed hunched over the board analyzing his sorry position.
The stage seems set for a dramatic finish, with both players within reach of the title. Chess experts who had written the champion off are beginning to reconsider.
In a game where psychology and sheer strength of will are vitally important, Kasparov has looked shaky in the last few days, and allowed himself to fall into serious time trouble early in Game 22.