Benoni Position - Should Black be Greedy?

Jan 8, 2013, 5:56 AM |

Recently, I have been having fun playing around with different d4 opening strategies as white. Playing against a friend of mine, the game quickly moved into the Modern Benoni Opening Line. Luckily, I have studied this a few times. After several moves, this eventually was the position. I spent some time thinking about this. See the included diagram:

I eventually decided on a5 in this position. This is a tough call. However, there are some very concrete reason for doing so. First and foremost I have to do something about black invading the queen side with a pawn advance. Notice how all my strength is on the queen side, and I have a space advantage due to the center pawn structure. Black threatens to destroy this with an agressive b5 pawn move. Now with the Bishop on d7, black is really threatening b5. It does not look like I can do much to stop it. However, does black's move on Bd7 have a consequence? I have noticed in chess every move has threats and consequences. The threat is obvious here. Is the consequence obvious? Before you quickly answer that the pawn on d6 is left undefended, that is not the immediate consequence. 

HINT: I am allowed to make a5 for a very concrete reason. Black can choose to be greedy and take the free pawn. However, is it free? Think. Is there any other consequence of Bd7 besides leaving the weak d6 pawn undefended?