As Black, I frequently struggle to find effective strategies against 1.d4 d5 2.c4.
While chess engines like Stockfish offer move suggestions, they often lack the underlying concepts and benefits of these moves.
I wish to decline the gambit, but what are the most optimal lines to do so?
If you start with 1. ... d5 you have two main choices: the Slav defence with 1. d4 d5 2. c4 c6 and the Queen's Gambit Declined (1. d4 d5 2. c4 e6).
The obvious difference between Slav and QGD is that c6 doesn't block the light squared bishop in. The less obvious difference is that your queenside in Slav with Bf5 is a bit wobblier than in QGD, since your b7 isn't protected.
You have a choice between:
There are also Schlehter and Chebanenko lines, but they are a rarer choice and I believe that Schlehter is a bit suspect.
The problem with Slav is exchange Slav. If you are in a must win situation and your opponent goes for it, you will have (at higher levels) a hard time finding any winning chances. The structure is too symmetrical and an open c-file facilitates heavy piece exchanges. On the bright side, white also has practically no winning chances.
For more about Slav check out IM Andras on YouTube. It's his recommendation in his Chessable courses, so he has also dedicated many instructive videos too it.
This is the most classical and principled approach. I think no matter which opening you choose, you should learn this one first and play it a few times at least.
I think best is to learn step by step, starting with historical approaches and progressing to modern TMB system.
As you see the big idea of all these approaches is for black to exchange off a few pieces, thus offsetting his space disadvantage and equalizing. If you want something sharper, you can also find it in the QGD:
However, as usual, the sharper the line is, the more theory is required.
You will see in high level games that a lot of the time these positions are reached via the 1. d4 Nf6 2. c4 e6 3. Nf3 d5 move order (after 3. Nc3 black would play 3. ... Bb4, going for the very reputable Nimzo-Indian defence). This is because black wants to lessen the sting of the annoying Queen's Gambit Exchange variation. On the plus side, QGD exchange is not drawish at all compared to Slav exchange. On the minus side, it's very very dangerous. White has two strong plans:
The above move-order avoids the second plan, since white cannot play f3 with a knight already on f3.
Don't forget also to prepare something against the Catalan. I think lines with Bb4+ are stronger than white players think and a bit less theoretical than mainline Open and Closed Catalans.
Even accepting the gambit is fine, just don't try to hold onto your extra pawn, the queen's gambit is not really technically a gambit. Black end's up in trouble when they waste tempo trying to hold onto the material advantage. Since the Netflix special a lot of players have been playing it, but my suspicion is that generally players who play the gambit are more familiar with the declined lines than the accepted ones.
I say accept the gambit, write off your extra pawn, develop, castle and play chess.
