Originally posted by richjohnsonHmm... sure nice to have a flight square, though the threat of forced retreat is hardly imminent - personally I'd avoid playing against threats that haven't materialised yet, and aren't guaranteed to materialise. If black intended to kick out the white bishop by a6 followed by b5, the a3 move could be played after it was clear that this is what black planned to do - after the a6 move. On the other hand, if black tried Na5 with the intention of trading at c4, I'd be quite happy with the position resulting from that trade! 🙂
9. a3 (since you're determined to have the bishop on c4, now there's an open square for when it's forced to retreat)
to recap:
1. e4 c5 2. Nc3 d6 3. Nf3 e5 4. Bc4 Nc6 5. Bb5 Bd7 6. O-O Nf6
7. d3 Be7 8. Bc4 O-O 9. a3
-Jarno