Chess Opening Theory/1. e4/1...e6/2. d4/2...d5/3. Nd2/3...Nf6/4. e5/4...Nfd7/5. Bd3/5...c5/6. c3/6...Nc6/7. Ngf3

Korchnoi gambit C05 French defence → Tarrasch → Closed Tarrasch → 6...Nc6 Universal system 7. Ngf3 · Korchnoi gambit 7. Ngf3 defends the d-pawn, but it prevents White from bringing their other knight to the defence of the pawn should Black increase the pressure. This gambit is sound for White. After 7...Qb6, the most common move, White has no good way to keep the d-pawn defended. 8. Nb3?? c4! forks the bishop and knight. 8. dxc5? Bxc5 gives up space and helps Black to develop. 8. Qa4!? is an interesting try. If 8...cxd4 9. cxd4 Qb4! 10. Qxb4 Nxb4 11. Bb1-, White has held on to the pawn. Instead, Black can bring another attacker by chipping away at the end of the pawn chain, 8...Be7! 9. a3 f6 10. exf6 Bxf6-, and White must give the d-pawn up. However, it transpires that sacrificing the pawn is sound, therefore the main move is 8. O-O and Black wins the pawn with 8...cxd4 9. cxd4 Nxd4 10. Nxd4 Qxd4. After 11. Nf3 (defending both d3, by discovery, and e5) Qb6, the main move is 12. Qa4. 12. Qa4 makes it hard for Black to develop cleanly, as the knight on d7 is pinned, and if Black develops their bishop, the queen can swing over to the kingside to pressure there: 12...Be7 13. Qg4! g6 14. Bh6+. Since Black is up a pawn they may instead wish to offer a queen trade: 12...Qb4 13. Qc2 Nc5 (attacking the bishop), then White can either engage in this little sequence 14. Bd2 Qa4 15. b3 Qd7 16. Be2+, or sacrifice the bishop in the hope of two pawns and a crushing attack, 12. Bxh7! g6 13. Bxg6 hxg6?? 14. Qxg6!+. 12. a3, allowing 12...Nc5 12. Bc2 but with the idea of b4, is an alternative. Black has several turn 7 alternatives since winning the pawn is not cut-and-dry. Black may wish to focus on completing their development with either 7...Be7 or 7...g6 intending ...Bg7. History This position was first reached by transposition from an open Tarrasch in a nine game match between William H. K. Pollock and Eugene Delmar, held in 1891.Pollock v Delmar, 1891. Chessgames.com Pollock was an English chess player and surgeon. Billed as the "champion of Ireland and Maryland", he lost the game and the match to Delmar.Delmar-Pollock, Skaneateles 1891. Chessgames.com It was reached again in 1929 by Frank Marshall, by transposition from an Indian defence. Marshall did not play with the idea of sacrificing d4. After 7...Qb6, he played 8. Qa4.Marshall v Saemisch, 1929. Chessgames.com The first appearance of 7. Ngf3 in the closed Tarrasch, with the idea of sacrificing d4, was played by Lev Abramov against Tigran Petrosian in 1947.Abramov v Petrosian, 1947. Chessgames.com Victor Korchnoi had a stunning execution of this sacrifice in 1967 against Mijo UdovcicKorchno v Udovcic, 1967. Chessgames.com. NB Korchnoi played a slightly different move order, with c3 and Ngf3 before Bd3. which led to some naming it the Korchnoi gambit.e.g. WGM Raluca Sgircea, IM Renier Castellanos (2015). Crushing French Defense – The Korchnoi Gambit. TheChessWorld.comSam Collins (2011). Korchnoi Gambit against the French. ChessBase. In his 2011 and 2016 books on the French, GM Simon Williams christens 7. Ngf3 the universal system for the set-up's utility against both continuations with 3...c5 and 3...Be7.Attacking Chess: The French Williams Simon Everyman 2011 9781857446463 260-286Killer French Williams Simon Self published. 2016 Theory table 0 7...Qb6 8. O-O cxd4 9. cxd4 Nxd4 10. Nxd4 Qxd4 11. Nf3 Qb6 12. Qa4 Qb4 13. Qc2 Nc5 + Korchnoi gambit 7. ... ... 8. ... ... 9. ... ... 10. ... ... 11. ... ... 12. ... Be7 13. Qg4! g6 14. Bh6 + 7...Be7 8. O-O O-O 9. Re1 f6 10. exf6 Nxf6 + References See also Analysis of Korchnoi vs. Udovcic, 1967: Sam Copeland (2020). Korchnoi Invents The Korchnoi Gambit. Chess.com blog.