Exchange Variation, Gligoric Variation

The Gligoric Variation is Black's most direct answer to the threat against e5 that castling creates in the Exchange Spanish. The pawn on f6 supports e5 firmly and leaves the queen and both bishops free to choose their squares. The cost is that it takes the natural square from the king's knight and leaves Black several moves from castling. White's standard reply, chosen in over half the games, is 6. d4, which opens the center while Black is still undeveloped. The main line, 6...exd4 7. Nxd4 c5 8. Nb3 Qxd1 9. Rxd1, trades queens and reaches an endgame in which the bishop pair must offset Black's damaged queenside. Black can instead pin with 6...Bg4, and White then usually keeps a central pawn presence with 7. c3. Quieter moves such as 6. c3 and 6. d3 are much less common. Engines consider the position balanced, and online results are nearly even.

The line became popular in the 1960s, when Boris Spassky was among its players. Svetozar Gligoric used it against Bobby Fischer at the 1966 Havana Olympiad in the 6. d4 Bg4 7. c3 line, and Spassky chose 6...exd4 7. Nxd4 against Fischer in their 1992 match.