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  8. f1e1  8... b7b6  9. b1a3  9... h7h6  10. c4d3 Solid and new. 10... c8b7  11. a3c4  11... e8g8  12. d1e2 Centralization and prophylaxis. 12... e6e5 Objectively speaking, a mistake. But such final games have their own  laws and we are not in the position to criticise any of the players'  decisions. 13. d4e5  13... d6e5  14. b2b3 It turns out that Black's position is very  unpleasant. f7-f5 is impossible, there are no outposts for the black  knights. And the rooks are not comfortable as the queen stays on their  road.