Mark Taimanov was awarded the International Grandmaster title in 1952 and played in the Candidates Tournament in Zurich in 1953, where he tied for eighth place. From 1946 to 1956, he was among the world's top ten players. He played in 23 USSR Chess Championships (a record equalled by Efim Geller), tying for first place twice. In 1952 he lost the playoff match to Mikhail Botvinnik, while in 1956, he beat Yuri Averbakh and Boris Spassky for the title. He is probably best known for his 6-0 loss to Bobby Fischer in the 1971 World Championship Candidates match. However, few players have beaten six world champions (Botvinnik, Vasily Smyslov, Mikhail Tal, Tigran Petrosian, Spassky, and Anatoly Karpov) as Taimanov has. Source: Mark Taimanov's Chess Biography on Wikipedia.