Leonid Stein

Stein had already qualified for the 1973 Petropolis Interzonal, and was considered a potential favorite to win the entire Candidates' cycle

Again, in 1967, Stein qualified for the Sousse Interzonal, scored well, in a tie for 6th–8th places, but had to undergo a further playoff with Samuel Reshevsky and Vlastimil Hort, in Los Angeles, which was won by Reshevsky.

He was on the Soviet side for the European team championships at Hamburg 1965 and Kapfenberg 1970, both of which were victorious. He served as an alternate on the Soviet team for the Match of the Century against the Rest of the World team, at Belgrade 1970. He played one game, losing to Larsen.

A very similar occurrence was the story of the next Interzonal tournament, in Amsterdam 1964. Stein took fifth place, sufficient for qualification for any non-Soviet player, with an outstanding total of 16½ / 23, but was blocked from advancement. He had finished behind fellow Soviets Mikhail Tal, Vasily Smyslov, and Boris Spassky, who, along with Danish GM Bent Larsen, had all scored 17 points. He did represent the USSR at the Tel Aviv Olympiad that year, scoring a fine 10/13, and winning an individual gold medal on the first reserve board. Again, he was in the Soviet side at the Havana Olympiad 1966, scoring 9/12, winning an individual silver medal on board four. Both times, the Soviet Union won the team gold medals.

Stein tied for third place in the 1961 Soviet Championship, at Moscow, defeating Tigran Petrosian on the way. He won his first Soviet title at Leningrad 1963; he tied with Boris Spassky and Ratmir Kholmov in the tournament itself, then won the playoff. He won again at Tallinn, 1965, and repeated the next year, 1966, at Tbilisi. Two outstanding international tournament victories were attained at Moscow 1967 (commemorating the 50th anniversary of the 1917 October Revolution), and Moscow 1971 (Alekhine Memorial, equal with Anatoly Karpov). Both of the Moscow tournaments were considered to be among the strongest tournaments in chess history up to that time. Further international tournament victories were scored at Sarajevo (Bosna) 1967, equal with Borislav Ivkov, Hastings 1967–68, shared, Kecskemét 1968, Tallinn 1969, Pärnu 1971, and Las Palmas 1973, equal with Tigran Petrosian. From 1963 to his premature death in 1973, Stein was in the top ten players in the world, or just outside that range.

With his strong result at the 1961 Soviet Championship, he earned the right to play in the 1962 Stockholm Interzonal tournament. His play there was excellent, finishing in a tie for 6th–7th places, but he was denied the right to advance to the Candidates' Tournament, because of a FIDE rule then in force which limited the qualifiers from any one country to three (in this case USSR). He had finished behind fellow Soviets Efim Geller, Petrosian, and Viktor Korchnoi.

In both 1955 and 1956, he tied for first place in the individual Army Championship. He achieved the national Master title for chess at the relatively late age of 24, but, as his Army titles against strong competition attest, he was likely at that strength somewhat earlier. At 24, he competed for the first time in the USSR Chess Championship at Tbilisi, 1959. In the following year he won the Ukrainian Championship at Kyiv, winning it again in 1962. He played board one for the Soviet team at the Helsinki 1961 Student Olympiad, scoring a strong +8, =3, −1, and helping his team to the overall gold medals.

Leonid Zakharovich Stein (Леонид Захарович Штейн; November 12, 1934 – July 4, 1973) was a Soviet chess Grandmaster from Ukraine. He won three USSR Chess Championships in the 1960s (1963, 1965, and 1966), and was among the world's top ten players during that era.