Mezue ahịrịokwu na-esonụ: Karpov gbalịrị 9...Nd7 ọtụtụ ugboro na
1990 World Championship egwuregwu, mana Kasparov nwetara uru dị ukwuu megide ya na egwuregwu nke 18. Ọ bụ ihe siri ike ma ọ dị ntakịrị. N'ụzọ na-agbagwoju anya 9...Nd7 ka a na-akpọ Chigorin Variation ya mere enwere ụdị abụọ nke Ruy Lopez nwere aha ahụ, mana 9...Na5 bụ mmegharị a na-ejikarị Chigorin eme. A makwaara nchekwa a dị ka mgbanwe Keres, mgbe Paul Keres.