!? The usual move is 4...Nf6. 4...g6 is playable here as White's queen on e3 Q/e3 hinders the activity of White's dark-squared bishop B/c1 on the weakened dark squares of Black's kingside.
5. Nb1c3 Bf8g7 6. Nc3d5
?! Better is 6 Bd2 or 6 Nf3, continuing the development.
6... Nc6d4
!? Black is bluffing. Better was 6...Nge7. Better was also 6...d6, played in the simultaneous exhibition game Fischer - Blackburne, in 1885.
7. Qe3d2
?! White makes developing the bishop B/c1 even harder. Better was 7 Bd3, defending the pawn P/c2 and developing one's bishop.