Chess Opening Theory/1. e4/1...d6/2. d4/2...Nf6/3. Nc3/3...g6/4. f4/4...Bg7/5. Nf3

=Austrian Attack=

5. Nf3
White supports e5 with his knight and threatens in earnest to advance his central pawns. Black has two choices. One is entirely defensive, but takes away from much of the force of the attack. The other, seen much more frequently than the former, is the choice of the world's top Pirc players.

Theory table

 * 1.e4 d6 2.d4 Nf6 3.Nc3 g6 4.f4 Bg7 5.Nf3