Chess Opening Theory/1. e4/1...e6/2. d4/2...d5/3. Nc3/3...Bb4/4. e5/4...c5/5. a3/5...Bxc3/6. bxc3/6...Ne7/7. Qg4/7...Qc7/8. Qxg7/8...Rg8/9. Qxh7/9...cxd4

Poisoned pawn variation Poisoned pawn variation 9...cxd4 Black captures the d4-pawn, opening up the queen and removing the defender of the e5-pawn. It might not be immediately clear how White should respond. 10. cxd4?? defends e5, but blunders 10...Qc3+ 11. Bd2 Qxa1+ ---. Defending just c3 with 10. Bd2? or 10. Bb2? fails due to 10...Qxe5+, taking the e5-pawn with check or 10...dxc3 gaining a tempo on the bishop. Therefore, White's best move by far is /10. Ne2/. This protects c3 and prevents 10...Qxe5 with 11. cxd4, regaining the pawn with tempo. This move does have one downside: the knight is in the way of the light-squared bishop, so it doesn't bring White any closer to castling. Also possible is 10. Qd3. White gives up the central pawns and offers a queen trade after 10...Qxe5+ 11. Ne2 dxc3 12. Qxc3. Black's best option is to take, after which the game has entered a queenless middlegame where White has a very dangerous passed pawn on the h-file. 10. Kd1 was common, but hasn't been played more than twice a year since 1999.https://www.chessgames.com/perl/chess.pl?page=5&node=87306 Theory table 10. Ne2 Nbc6 11. f4 Bd7 12. Qd3 dxc3 10. Qd3 Qxe5+ 11. Ne2 dxc3 12. Qxc3 Qxc3 13. Nxc3 Nbc6 References French Defence Winawer_Variation:_3.Nc3_Bb4