soheil_hooshdaran wrote:What happens after
13...Nc6 14.Nd5 in:
My immediate thought was that White wins, which makes it puzzling as to why none of the players (including Karpov) who have reached this position have played it. A quick check with an engine reveals the resource. After 14. .. exd5 15. cxd5, Black has Nc5, hitting the Queen and blocking the c file. The suggested line after that is 16. Rxc5 dxc5 17. Nxc6 where White has sacrificed the exchange for a pawn and compensation.
A useful resource to know, as allowing Nd5 in such positions is usually best avoided.