4.d4 D6
Alternatively, Black generally tries to hold the center with 4...d6, when White has a choice of plans, each of which should be enough to secure a slight advantage. White can simplify to a slightly better queenless middlegame with 5.dxe5 dxe5 (5...Nxe5? 6.Nxe5 dxe5 7.Qh5! and White's double attack on e5 and f7 wins a pawn) 6.Qxd8+ (6.Bd5!? is also possible) Bxd8 7.Nc3 Nf6. White can also close the center with 5.d5 Nb8, followed by Bd3 and expansion on the queenside with c4, resulting in positions resembling those from the Old Indian Defense. Finally, with 5.Nc3 White can retain tension in the center and obtain active piece play.
Harding and Botterill, in their 1977 book on the Italian Game, conclude that, "The Hungarian Defence can only be played for a draw. White should have an edge in most lines."
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