Chess Opening Theory/1. d4/1...d5/2. c4/2...dxc4/3. Nc3/3...f5

3...f5?
This move is too weakening. It weakens the entire e-file, and the c4-g8 diagonal. In Match 1, Game 8, Labourdonnais-McDonnell, McDonnell played f5 and lost quickly.

Labourdonnais-McDonnell

 * 1) d4 d5 2. c4 dxc4 3. Nc3 f5? 4. e3 e6 5. Bxc4 c6 6 Nf3 Bd6 7 e4	b5 8.	Bb3	a5 (Horrible, but he had a very bad game in any case) 9 exf5 exf5 (The open e-file, central king and open a2-g8 Diagonal promise a quick and painful demise for black). 10.	O-O	a4 11. Bxg8 Rxg8 12.	Bg5 Qc7 13. Qe2+?! (Re1+! was much stronger)	Kf8 (Kf7 was better, though after Rfe1, White's advantage is beyond dispute) 14. Rfe1	Kf7 15. Rac1	Qb7 16 d5! h6 17. dxc6 Qa6 18. Nxb5 hxg5 19. Nxd6+ Kg6 20. Ne5+ Kf6 21. Qh5 g6 22. Qh7 Be6 23. Nxg6 Nxc6 24. Rxc6 Qd3 25. Qe7+ Kxg6 26. Rxe6+ Kh5 27. Qh7+ Kg4 28. Rc4+ f4 29. h3+ Qxh3 30. Qxh3#