I would say that Sergei Prokofiev, who defeated Capablanca (Capablanca!) in a simultaneous game while the latter was still World Champion, is a strong contender.
Capablanca lost very rarely in chess - even in his simuls.
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On another note, comments #11 and #20 were reported for antisemitic content. Such drivel (both the people and what they spout) is never tolerated in these pages.
Kubrick and Nabokov were working together during the filmation of "Lolita", but it seems like there aren't any recorded games between them. I wonder how it's possible.