Martina Navratilova, a four-time champion and the No. 2 seed this year, withdrew yesterday from next week's Virginia Slims Championships because of knee problems.

Navratilova, who earlier this year won a record ninth Wimbledon singles title, pulled out of the $3 million year-ending tournament because of bone degeneration and calcium deposits in her right knee, although she said both knees have been bothering her.

"I will have both knees 'scoped next Wednesday," she said, referring to arthroscopic surgery. "Both knees have been pretty bad this year, on and off." She said the operations will be performed by Richard Steadman at the Vail Valley Hospital in Vail, Colo., near her Aspen home. . . .

Mats Wilander of Sweden and Marcelo Filippini of Uruguay easily won their matches to qualify for the final of the Citibank tournament in Itaparica, Brazil. Wilander beat Mark Koevermans of the Netherlands, 6-4, 6-3, and Filippini topped Thomas Carbonell of Spain, 7-6, 6-4. . . .

American Tim Mayotte beat fifth-seeded Alexander Volkov of the Soviet Union, 6-3, 6-2, to gain the semifinals of the Kremlin Cup in Moscow. In the other quarterfinals, Soviet Andrei Cherkasov ousted Emilio Sanchez of Spain, 6-3, 6-3; Peter Korda of Czechoslovakia beat Anders Jarryd of Sweden, 7-5, 7-6, and Udo Riglewski of Germany beat Sergio Casal of Spain, 4-6, 7-6 (8-6), 6-3.