Chess Opening Theory/1. e4/1...Nf6/2. e5/2...Nd5/3. d4/3...d6/4. c4/4...Nb6/5. exd6/5...cxd6

=Alekhine's Defence= White still has a space advantage, but Black is intending to attack the c- and d-pawns with moves like ...Nc6 and ...Bg7. Meanwhile, White has not yet moved any pieces and needs to develop. Most modern masters prefer to delay playing Nf3, since such a knight can quickly become a target to ...Bg4, so the most common move is 6.Nc3.

Theory table
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'1.e4 Nf6 2.e5 Nd5 3.d4 d6 4. c4 Nb6'