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Chess Opening Theory/1. e4/1...Nf6/2. Bc4/2...Nxe4
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Krejcik variation B02 Alekhine's defence → Krejcik variation
2...Nxe4
White's only way to recover the pawn is 3. Bxf7+. Black can take the bishop but White wins the knight in trade through the sequence 1. e4 Nf6 2. Bc4 Nxe4 3. Bxf7+ Kxf7 4. Qh5+ Kg8 5. Qd5+ e6 6. Qxe4 d5 7. Qe3 e5 -.
Theory table
3. Bxf7+ Kxf7 4. Qh5+ Kg8 5. Qd5+ e6 6. Qxe4 d5 7. Qe2 e5 8. Qxe5 Nc6 9. Qe3 -- Krejcik variation
References
Alekhine Defence