1.Nf3 f6 2.e3 e6 3.Nd4 c6 4.Nb5 cxb5 5.Qh5+ g6 6.Qb5 Nc6 7.Qb6

If 7...axb6 (7...Qxb6 is even worse) then 8.Bb5 Kf7 (only move) 9.Bxd7 and the endgame obtained after 9...Rxa2 10.b4 is winning for white, so black has to play 7...Kf7.