Anatoly Karpov was surprised and thrown off balance in the second game of his world championship chess match with Victor Korchnoi. But the champion managed to hold a draw, in a hectic game that drew another charge of foul play from the challenger.

After the game was ended, the Korchnoi camp lodged a formal protest, claiming that a container of yogurt, sent to the champion late in the game, may have concealed a secret message.

"It is clear that a cunningly arranged distribution of edible items to one player during the game emanating from one delegation or the other could convey a kind of code message," the Korchnoi statement said.

"Thus a yogurt after move 20 could signify 'We instruct you to offer a draw' or a slice of mango could mean 'we order you to decline a draw' or a dish of marinated quail's eggs could mean 'Play knight to knight five at once' and so on. The possibilities are endless."

The protest cited the Chess Federation's rule that "no extra equipment" be delivered to a player during a game, and said that this includes food. Korchnoi came to the game equipped with a thermos of tea and honey, which he sipped while Karpov was deliberating is moves.

The game itself, the second draw in a row, "was a better draw than the first draw," said grandmaster Lubomir Kavalek of Reston, one of America's leading players.

Korchnoi used the open variation of the Ruy Lopez, a fighting defense that served clear notice he was out for blood after the tane first game. After exchanging both bishops for knights, he pressed the attack with his two advanced knights until Karpov, on his 22nd move, made and obvious bid for a draw.

The game lasted 29 moves - 3 1/2 hours. Karpov took 50 minutes for his first 15 moves while Korchnoi took four. This time differential reflected Korchnoi's choice of an operning variation relatively unfamiliar to his opponent (who had undoubtedly been expecting a French Defense) and one that contained a number of tricky positions and complicated traps.

The champion's moves in the middle game (particularly moves 10 through 22) indicated a slight feeling of insecurity, a desire to simplify the complex position, although some analysts might have given him a slight edge with two bishops against two knights. He avoided moves which might have made a draw less likely, such as 13. BxN (with wild complications) or 16. P-KN4 (which would have allowed the powerful 16. . .PQS), choosing the least speculative continuation at each point.

British grandmaster Raymond Keene, one of Korchnoi's seconds, said that the challenger will change his strategy in the next game, tomorrow, when he will have the white pieces.