1. c4 Nf6 2. g3 e6 3. Bg2 d5 4. Nf3 dxc4 5. d4

My question is why doesnt black play cxd4? Database says no masters played it, but I can't see why. Anyone help me see what I'm missing? Is it that white just gets a quick lead in development or is there a tacical shot?

From the position after dxc4 I don't have a single occurance of 5.d4 in my database. I have Qa4, 0-0, Qc2, Na3, Ne5, a4, and Nc3, all of which make sense. The position after 5.d4 is a standard Catalan tabiya, however move order is different so your move is not possible.

Do you mean dxc3? I don't see any tactical shots from that position, but maybe a higher-rated player can explain why no masters played it.

He means cxd3, capturing en-passant. 

Probably because your database (Blaken's) only shows games that had an earlier d4 and reached that position through transposition (so cxd3 is not legal).

what pellik said.

An example of this move order thing in databases is this:

Go to chess com game explorer.
Play 1.d4 d5
Look at  2.e4 and see how many times it has been played (about 400)
Now after 2.e4 it says ..e6 has been played 80,000 times!!!!

This is because the position usually arrives from the order 1.e4 e6 2.d4 d5 and is called the french defense. The database notices the transposition and so adds the games to the move count.


Your position most likely came about from a move order like:

The database recognises the transposition and so will say that there are many many games in the database from this position.
However NONE of them will have arrived there after 5.d4, this is why no one has played cxd3.

So is cxd3 (which I meant to type) a good move?

yes, if you are black and white plays 5.d4 for some reason it should be a good move. White will be left with a weak pawn on d3.

Thanks, i did mean cxd3.

It also gets rid of black's weakness on c4 and leaves black a clear pawn up. White should never play 5. d4 there, which is why all of the games are from the other position.

Where the other move order is used and this is feasible, it isn't an English, it's a Catalan, and in fact a popular position so it is no wonder your database picks up so many games.  It probably did not occur from the English move order even once.