World Chess Field Narrowed in Tunis

The list of potential challengers for the 1986 world chess championship was narrowed Monday by the results of an interzonal chess tournament in Tunis, an early stage of world championship competition.

Only four of the 18 competitors in the tournament, the first of three interzonals this year, advance to the next round--the Candidates Tournament, scheduled for October in Montpellier, France.

Artur Yusupov, a 25-year-old grandmaster from the Soviet Union, won seven games in the Tunisian capital and drew nine to win the tournament with a score of 11 1/2-4 1/2. He was the only undefeated player. His countryman Alexander Beliavsky, 31, took second place at 11-5. Lajos Portisch, 48, of Hungary was third at 10-6.

In tournament chess, victories count for one point on the winner’s side and draws for one-half point.

Two more Soviet players, Alexander Chernin, 24, and Viktor Gavrikov, 27, tied for the final qualifying spot with 9 1/2-6 1/2 scores. They will break the tie with a match to be played in the next week or two.

Chernin’s play startled the chess world. Less than a year ago, he was virtually unknown, but then he tied for first in the Soviet championship in February. He is the only one of the top finishers in Tunis without the title of grandmaster.

The two U.S. representatives did about as expected. Max Dlugy, 19, of New York, tied for sixth place, at 9-7, and Nick de Firmian, 27, of Oakland, was ninth, with 8 1/2-7 1/2.

The other interzonal tournaments begin June 27 in Mexico City and July 1 in Biel, Switzerland.

The 1984 championship has not yet been decided. Anatoly Karpov and Gary Kasparov, both Soviet citizens, will play for the title in September. In 1986, the winner of that match will face the challenger selected by the candidates’ competition.