[%c_effect d4;square;d4;type;GreatFind;persistent;true] It's not the first and it won't be the last time that this advance decides a game in a hanging pawn's position.
1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. b1c3  3... f8b4  4. e2e3  4... e8g8  5. f1d3  5... d7d5  6. c4d5  6... e6d5  7. g1e2 I must admit that I have a certain prejudice with those lines in the Nimzo-Indian in which White has the dark-squared bishop inside the pawn chain and not outside (on f4 or g5), as would be ideal. Considering the level of chess players who play this variation with White, I think it's time to review my prejudices. White's main plan is to play f3-e4 at some point, but Black also has a possible break on c5. 7... f8e8  8. c1d2  8... b4d6 Just because the bishop went to b4 one day doesn't mean it should capture on c3. This withdrawal is useful, in order to point the bishop toward the white king, which will go to g1. 9. d1c2  9... a7a6 A useful move to avoid 10.Nb5. The c-pawn stays on its starting square to be advanced all at once to c5. 10. e1g1  10... b8d7  11. a1d1 A new move. 11... b7b6 This move gives White some options. Another idea is to advance …c7-c5 immediately. 12. a2a3 [%c_effect a3;square;a3;type;Inaccuracy;persistent;true] This move is a bit slow. 12... c7c5  13. d4c5  13... b6c5 We now have a classic hanging pawns structure, this formation in which two \"friends\" are in the middle of the board, without the possible protection of other pawns. This friendship often leads to many adventures. Sometimes one of these pawns is lost or sacrificed along the way. This is a good version for Black, as the white pieces are somewhat passive. 14. c3a4 [%c_effect a4;square;a4;type;Mistake;persistent;true] This makes things worse. \"A knight on the rim is dim.” I never get tired of this quote. 14... g7g6 [%c_effect g6;square;g6;type;Interesting;persistent;true] This is always a useful move, giving some air to the king, restricting the d3-bishop and taking away his square on f5. 15. b2b3  15... c8b7  16. h2h3  16... d7e5  17. d2c3  17... a8c8  18. c2b1 [%c_effect b1;square;b1;type;Inaccuracy;persistent;true] This is a fatal mistake, although White's situation is already very dangerous. Black has a position typical of a book chapter \"Hanging Pawns,” in which the author explains the ideal development for the pieces and shows games in which the …d5-d4 advance is executed to open the position of the bishops and start a devastating attack. A pity that when we play our games things are not as easy as they are in book chapters, real or imaginary. Sevian makes everything look simple.