Leningrad 1973 Interzonal

The Leningrad Interzonal was the first ever held in the Soviet Union, and it ended with two future world-title contenders sharing first: Viktor Korchnoi and the 22-year-old Anatoly Karpov, level on 13½/17. It was the tournament where Karpov showed he was a real contender for the title.

◇The first Interzonal in the USSR

Because the 1973 cycle had two Interzonals — Leningrad and Petropolis — each qualified only its top three finishers for the Candidates matches. Eighteen players contested a single round-robin over seventeen rounds in June 1973, in a hall filled through the white-nights weeks around the summer solstice.

The field included Korchnoi, the rising Karpov, Robert Byrne, Mikhail Tal, Bent Larsen, Robert Hübner, Svetozar Gligorić and Jan Smejkal. Only three places were on offer, which made every half-point decisive.

◇Two Soviets share the lead

Korchnoi and Karpov pulled clear together and finished level on 13½/17. Korchnoi scored eleven wins with a single loss; Karpov went through the event unbeaten, with ten wins and seven draws. Robert Byrne took the third qualifying place on 12½, and Jan Smejkal — who reeled off six straight wins in mid-event — fell just short in fourth on 11.

Both leaders secured qualification with a round still to play. Karpov, in his first Interzonal, had matched one of the strongest and most experienced grandmasters in the world.

“Along with the tournaments of 1968, I rate the Leningrad Interzonal as one of the best achievements of my life.”

◇The start of a decade's rivalry

Korchnoi, Karpov and Byrne joined the Petropolis qualifiers — Henrique Mecking, Lajos Portisch and Lev Polugaevsky — along with the seeded Tigran Petrosian and Boris Spassky in the 1974 Candidates. Karpov won that cycle and, when Fischer declined to defend, became World Champion in 1975.

Leningrad was thus the first stage on which the Karpov–Korchnoi relationship, which would dominate world championship chess for the rest of the 1970s, played out. Korchnoi later ranked the event among the finest achievements of his career.