Mikhail Botvinnik, Tigran Petrosian, Anatoly Karpov, Garry Kasparov, and Magnus Carlsen have employed it during their world championship matches. Bobby Fischer created a stir when he switched to it from his customary 1.e4 late in his career, employing it against Lev Polugaevsky and Oscar Panno at the Palma de Mallorca Interzonal in 1970, and in his world championship match against Boris Spassky.