Blocking the check with the knight
1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.c3 Nf6 5.d4 exd4 6.cxd4 Bb4+ 7.Nc3 Nxe4
- The mistake
- Meeting the check on b4 with 7.Nc3, as though it were a developing move that happens to block.
- Why it costs
- It is not a developing move, it is a gambit. 7…Nxe4 takes the pawn and hits the knight, and the compensation only exists for someone who already knows 8.O-O Bxc3 9.d5 — the Greco Attack. Reached by accident, it is a pawn for nothing.
- Instead
- 7.Bd2, which blocks and defends at the same time, and leaves an ordinary position where White is a little more comfortable.