Chess Opening Theory/1. e4/1...Nf6/2. e5/2...Nd5/3. d4/3...d6/4. c4/4...Nb6/5. exd6/5...cxd6/6. Nc3

=Alekhine's Defence= Black would very much like to put pressure on the d-pawn with ...Nc6 and ...Bg7. Playing 6...Nc6 now however runs into d4-d5, maybe even on the next move, and the knight will find itself kicked around the board. So Black is in most games patient, and plays 6...g6 to prepare 7...Bg7.