the 1957 Wageningen Zonal, he tied for 3rd–4th places, along with Donner, with 12½/17; there were only three qualifying berths, so the two players had to dispute a playoff match. Larsen won by 3–1 over Donner at The Hague 1958 to qualify for his first Interzonal, at Portorož 1958. Larsen could score only 8½/20 for 16th place, and was not close to qualifying. But he scored his first major individual international success by winning Mar del Plata 1958 with 12/15, ahead of William Lombardy, Erich Eliskases, Oscar Panno, and Hermann Pilnik. Larsen went into a slump beginning with the 1958 Interzonal. He tied 5th–6th in a strong field at Zürich 1959 with 9½/15, behind winner Tal, Gligorić, Paul Keres, and Bobby Fischer. But Larsen placed only 4th in a middle-range field at the 1960 Berg en Dal Zonal 1960 with 5½/9, and did not advance to the Interzonal. He recovered by sharing 1st–2nd places at Beverwijk 1961 on 7½/9 with Borislav Ivkov. At Zürich 1961, he tied for 6th–7th places with 6/11, as Keres won ahead of Tigran Petrosian. At Moscow 1962, he shared 7th–11th places with 7½/15 (Yuri Averbakh won). Challenging for the World title Around this time Larsen diversified his style, switching over to risky and unusual openings in some of his games, to try to throw his opponents off balance; this led to the recovery of his form and further development of his chess. He finished 2nd at the 1963 Halle Zonal with 13/19, behind winner Lajos Portisch, to advance to the Interzonal the next year. At Belgrade 1964, he shared 5th–6th places with 10/17 (Boris Spassky won). He tied for 5th–7th places at Beverwijk 1964 on 9½/15; Keres and Nei won. Larsen's unusual openings were on full display at the 1964 Amsterdam Interzonal, where he shared the 1st–4th places on 17/23 with Boris Spassky, Tal, and Vasily Smyslov, advancing as a Candidate. In the 1965 Candidates' matches, he defeated Borislav Ivkov at Bled by 5½–2½ but lost a hard-fought semifinal, also at Bled by 4½–5½ to former World Champion Mikhail Tal, who won the tenth game with a complex speculative knight sacrifice in the center. Larsen won a playoff match for alternates, an eventual third-place Candidates' position, against Efim Geller by 5–4 at Copenhagen 1966 (the first time a Soviet grandmaster had ever been beaten by a non-Soviet in a match). In 1967 he won the