He was one of few players to have plus records against Capablanca, Euwe and Tal, and he also had equal records against Smyslov, Petrosian and Anatoly Karpov. In his long career, he played 10 world champions. He won at least one game against all from Capablanca to Bobby Fischer (his two games with Karpov were drawn), making him one of only three players to beat nine undisputed world champions (the other two are Victor Korchnoi and Alexander Beliavsky). Other notable grandmasters against whom he had plus records include Fine, Flohr, Viktor Korchnoi, Efim Geller, Savielly Tartakower, Mark Taimanov, Milan Vidmar, Svetozar Gligorić, Isaac Boleslavsky, Efim Bogoljubov and Bent Larsen.