Catalan with 4...Bb4+ 5.Bd2 Be7 is variation 5 of 6 in the Catalan Opening course, a advanced opening course for White (ECO E01). It runs 22 moves and begins 1. d4 Nf6 2. c4 e6 3. Nf3 d5 4. g3 Bb4+ …. Black inserts ...Bb4+ to lure the c1-bishop to d2, then retreats to e7. White's bishop is slightly misplaced on d2, so it often comes back to f4 after Qc2. In the lesson every move is explained on a board and then drilled; it is free.
Move by move
1. d4 – White takes the centre.
1... Nf6 – Black develops.
2. c4 – White gains space.
2... e6 – Prepares ...d5.
3. Nf3 – Develops.
3... d5 – Black takes the centre.
4. g3 – The Catalan fianchetto.
4... Bb4+ – Black gives a check to make White decide how to block before the bishop goes to g2.
5. Bd2 – The bishop blocks; White does not mind trading dark-squared bishops.
5... Be7 – The bishop retreats: Black has lured White's bishop to d2, where it is less active than on its natural squares.
6. Bg2 – The bishop goes to the long diagonal.
6... O-O – Black castles.
7. O-O – White castles.
7... c6 – Black supports d5 to keep the long diagonal closed.
8. Qc2 – The queen controls e4 and prepares Bf4 and Nbd2.
8... b6 – Black prepares ...Ba6 to pressure c4 or ...Bb7.
The lesson goes on for 6 more moves, each with its explanation.
chessGM