1. e2e4  1... e7e5  2. g1f3  2... g8f6  3. f3e5  3... d7d6  4. e5f3  4... f6e4  5. d2d4  5... d6d5  6. f1d3  6... c8f5 This is a popular variation of the Petroff these days, being a specialty of super GM Duda, who played it in the candidates tournament. GM So also knows this line well, having scored an important victory with black against Niemann in the Sinquefield Cup with it. 7. e1g1  7... f8e7  8. f1e1  8... e8g8  9. b1d2  9... e4d6  10. d2f1  10... c7c6  11. c1f4  11... f5d3  12. d1d3 