aka. King's Fianchetto Def.

Board Position
An increasingly popular side-defence against both KP and QP openings, where Black aims for asymmetrical positions, using a fianchettoed king's bishop (move 2b, left) to attack White's centre. Board Position
Black's build-up is similar to the Pirc Defence (qv.) except that the development of his king's knight is delayed to avoid a White B-KKt5 attack. There are also similarities with the Kotov-Robatsch Defence.
Highly flexible, it was first analysed by the Austrian GM K.Robatsch in the 1950's, but popularised by young British players (who called it the "Modern") in the 1970's. As in the Pirc, White generally has to decide whether to proceed modestly or annex the entire centre (as in move 5w, right).
Clear or
see: (KP game): 1 e4 g6 2 d4
(QP game:) 1 d4 g6 2 e4
for 2..Bg7 3 c3 d6 4 f4 Nf6 5 Bd3 0-0 6 Nf3 c5 7 0-0 cxd4 8 cxd4 Nc6