1. e2e4  1... d7d6  2. d2d4  2... g8f6  3. b1c3  3... e7e5  4. g1f3  4... b8d7  5. g2g4 Shirov is fond of playing the g4-move in the opening. White can consider this idea without sacrificing the pawn, playing 5.Rg1 first. 5... f6g4 Accepting the gift.