1. d2d4  1... g7g6 A fact: nowadays, the decisive games often see some irregular  opening choices. The Pirc/Modern defenses are notorious for that. Some  examples that come to my mind are Ivanchuk-Kramnik, FIDE Candidates'  London 2013 and Karpov-Kortschnoi, Baguio City 1978. 2. g1f3  2... f8g7  3. e2e4  Shifting to the Modern/Pirc. 3... d7d6  4. f1c4  4... e7e6 Keeping it as original  as possible. 5. e1g1  5... g8e7  6. a2a4  6... b8d7 Spassky used a similar set-up in his first match against  Petrosian in order to avoid the theoretical lines. Later, however, he  admitted it was a mistake and he went for the main lines in their second  match in 1969. 7. c2c3  7... a7a5 