1. Open Catalan: 5...a6 6.O-O Nc6 7.Qc2 b5

Against 5...a6 and 6...Nc6 White attacks the c4 pawn with Qc2. Black defends it with ...b5, but after 8.a4 Bb7 9.axb5 axb5 10.Rxa8 Bxa8 the b5 pawn is left without defense.

1.d4 Nf6 2.c4 e6 3.g3 d5 4.Bg2 dxc4 5.Nf3 a6 6.O-O Nc6 7.Qc2 b5 8.a4 Bb7 9.axb5 axb5 10.Rxa8 Bxa8

Move by move

1.d4 – White occupies the center with the Queen's pawn: it controls e5 and c5 and prepares c4, the first step of the Catalan.
1...Nf6 – Black develops the Knight and controls e4: it postpones the choice between ...d5, ...e6 and the Indian defenses.
2.c4 – White gains space with the c-pawn: it controls d5 and prepares Nc3 or the g3 fianchetto.
2...e6 – Black opens the f8 Bishop and prepares ...d5: this is the structure of the Queen's Gambit Declined, against which the Catalan is designed.
3.g3 – The Catalan: White prepares the fianchetto on g2, from where the Bishop will aim at d5 and the whole Black queenside.
3...d5 – Black occupies d5: now the g2 Bishop will have a pawn in front of it, but the c4 pawn attacks it and the tension remains.
4.Bg2 – The Bishop settles on the long diagonal: it presses on d5 and, if Black captures on c4, it will hit b7 and a8.
4...dxc4 – The Open Catalan: Black takes the c4 pawn and frees d5, but opens the diagonal of the g2 Bishop. White will recover the pawn with Qa4+, Qc2 or Ne5.
5.Nf3 – White develops the Knight and prepares castling: it is in no hurry to recapture c4, because the pawn is hard to hold.
5...a6 – Black prepares ...b5 to hold the c4 pawn; in return it postpones the development of the kingside.
6.O-O – White castles and still leaves the pawn to Black: development first, then the recovery with Qc2 or Ne5.
6...Nc6 – The Knight comes out to c6 and presses on d4: it prepares ...Rb8 and ...b5, or ...Nb4.
7.Qc2 – The Queen attacks the c4 pawn and controls e4: Black must defend the pawn with ...b5 or give it back.
7...b5 – Black defends c4 with the b-pawn: now the chain a6-b5-c4 holds the pawn, but the Black queenside is weakened.
8.a4 – White attacks the pawn chain at its base: if the b5 pawn falls, c4 too will be left without defense.
8...Bb7 – The Bishop develops to b7, faces the g2 Bishop and protects the a8 Rook on the diagonal.
9.axb5 – White exchanges on b5 and opens the a-file, where its a1 Rook is already ready.
9...axb5 – Black recaptures with the a-pawn: the b5 pawn remains, but it no longer has any pawns protecting it.
10.Rxa8 – White exchanges the Rooks on the a-file: without the a8 Rook, Black has one defender fewer for the b5 and c4 pawns.
10...Bxa8 – The Bishop recaptures on a8 and stays on the long diagonal facing the g2 Bishop.

How to exploit the position

Black has an extra pawn, but the b5 and c4 pawns are weak and White has better development.

Play Nc3: the Knight attacks b5, which no longer has pawns to protect it. If ...b4, the Knight goes to b5 or e4.
With b3 attack the base of the chain: if ...cxb3, the Queen recaptures and hits b5.
The push e4 followed by d5 hits the c6 Knight and shuts in the a8 Bishop.
Do not take on c4 with the Queen as long as the b5 pawn defends it.

Master tips

The g2 Bishop against the queenside

When Black takes on c4 and pushes ...b5, its pawn chain becomes a target: the g2 Bishop and the push a4 attack it.