comment: The only way to fight for an advantage.
context: 1. d2d4  1... g8f6  2. c2c4  2... e7e6  3. b1c3  3... f8b4  4. e2e3  4... b7b6 Black has many options in this classic Nimzo-Indian line. 5. f1d3  5... c8b7  6. g1f3  6... e8g8  7. e1g1  7... c7c5  8. c3a4 This move highlights the problem of not capturing the knight earlier. If you play similar positions with Black, always watch out when White castles and gets rid of the knight pin. If you forget about it, you might find yourself with a trapped bishop. 8... c5d4 The bishop prepares to come back. 9. a2a3 There's a small detail White has to keep in mind when choosing this instead of 9.exd4. In 1999, I played 9.a3 with White and thought I was very clever doing so, but fifteen minutes later, I wasn't sure anymore. Actually, I'm still not sure about it 25 years later. 9... b4e7  10. e3d4  10... d8c7 I didn't know this move. I used to play 10...d6, when White is slightly better but it's not a big deal. 11. f1e1 This prevents 11...Ng4, which can simply be answered by 12.h3, but allows Black to play 11...d5. 11... d7d5 