The Nimzo-Indian: pin the knight and argue about the centre

The key idea

The ...Bxc3 trade isn't made for tactical reasons: it's made to leave White with doubled pawns on c3 and c4. From there Black plays against those pawns — blockading with ...c5 and ...d5, trading pieces — and White plays against the clock, trying to open the game so his two bishops outweigh his structure.

Example 1 · The deal, seen from Black's side

After 4.e3 O-O 5.Bd3 d5 6.a3 Bxc3+ 7.bxc3 the doubled pawns are already on the board. Watch what Black does with them.

1. dxc4 First decision, and it defines the plan: I trade on c4 so he's left with ONE doubled pawn on c3 rather than a c3-c4 chain that defends itself. Look at what I've just bought — the c3 pawn can never be defended by another pawn, because its b-file neighbour no longer exists and the d-pawn is busy in the centre.
2. Bxc4 White recaptures with the bishop, which also lands on the good diagonal pointing at f7. His compensation is this: two bishops and a centre that can grow with e4.
3. c5 And here's the thematic blow of the whole opening. I press d4, the pawn that holds White's centre up; if it falls or gets traded, the c3 pawn is left alone in the middle of the board with no neighbours and nothing to do. In the Nimzo-Indian you don't attack the weakness directly: you attack what protects it.
4. Ne2 The knight via e2 rather than f3, so as not to block the f-pawn and to be able to prepare f3 and e4. White knows his only asset is opening the game.
5. Qc7 The queen to the c-file, on the same line as the doubled pawns. Every piece I place is looking at the same spot.
6. Ba2 The bishop steps out of the trade and keeps the diagonal.
7. b6 I'm preparing ...Bb7 or ...Ba6 to trade off his best bishop. That's the Nimzo-Indian's second plan: trade pieces. Every set of pieces that leaves the board brings the endgame closer, and in an endgame a doubled pawn has no possible compensation.
8. Bb2 A level position. The honest valuation: the engine calls it a clean draw, so the deal is fair — I haven't gained anything by making the trade, I've swapped one kind of advantage for another. White has two bishops and space while the game stays closed; I have a permanent weakness to aim at once it opens.

Example 2 · And the White player who doesn't want doubled pawns

With 4.Qc2 White prepares to recapture with the queen. Now White is teaching: structure intact, and the price paid for it.

1. d5 I recaptured with the queen, so my pawn structure is untouched: not one doubled pawn on the board. And I have the bishop pair. What I've paid for it is two tempi — a3 and the queen's journey — and having the queen committed early, where she can be hit.
2. e3 I shut the house and free the f1 bishop. No hurry: my advantage doesn't expire.
3. c5 Black strikes the centre, just as in example 1. It's his plan in both variations.
4. dxc5 And I capture. With the bishop pair it pays to open positions, even at the cost of simplifying: two bishops on a clear board are worth considerably more than two bishops behind a wall of pawns.
5. Ne4 The knight jumps into the centre with tempo, hitting my queen. Note this — it's the bill for bringing her out on move 4.
6. Qc2 The queen retreats to a useful square. A tempo lost, yes — and in exchange I have no pawn weakness to drag around for forty moves.
7. a5 Black gains space on the wing before recovering the c5 pawn.
8. cxd5 And I open the centre. The balance of both variations together, which is what to take from this lesson: with 7.bxc3 White buys a big centre and pays with doubled pawns; with 4.Qc2 he keeps the structure and pays with tempi. Both are good and both give rough equality. Choosing between them is choosing what kind of game you want to play.

Practice

You've just given up the bishop on c3 and White has recaptured with the pawn: there's his permanent weakness. You're Black. Don't attack it head-on — go for what holds it up.

1. That leaves the c3 pawn on its own. While the c3-c4 chain existed, the two of them defended each other. Capture on c4 so he's left with a loose doubled pawn instead of a chain that holds itself up.
2. The thematic blow. You're not attacking c3: you're attacking d4, which is what holds White's whole centre together. Strike the centre with the pawn that hasn't moved yet, pressing d4.
3. The queen onto the file of the doubled pawns. All your pieces looking at the same spot. Put the queen on the file where his weakness lives.
4. And you prepare the fianchetto to trade off his best bishop. Every piece that leaves the board takes you closer to the endgame where a doubled pawn has no compensation. Prepare your c8 bishop's route to the long diagonal.

That's the whole mechanism of the Nimzo-Indian, and you haven't had to memorise a single line: you give up the bishop to create a weakness that never heals, you attack what holds it up rather than the weakness itself, and you trade pieces to reach the endgame where it tells. Keep the other half too, which is what makes this opening honest: while the game stays closed, his two bishops are worth as much as your doubled pawn. The game is about who gets the type of position that suits them.