A sign for the courage. "It  is not mate if I mate you first."
1. e2e4  1... e7e5  2. g1f3  2... g8f6 Challenging Caruana on his own territory, and this is not for the first time! The American GM basically paved his way for the  WWC holding the black color in Berlin Candidates with the Petroff, whereas the Polish GM has the defense as a major part of his repertoire. 3. f3e5  3... d7d6  4. e5f3  4... f6e4  5. b1c3 The sharpest reply against the Petroff. 5... e4c3  6. d2c3  6... f8e7  7. c1e3  7... b8d7  8. d1d2  8... e8g8  9. e1c1  9... d7f6  10. f1d3  10... c7c5 [#] 11. h1g1 A novelty. And a venomous one. White is  ready to advance the g-pawn. 11... b7b5 After some reflection, Duda answers in the most aggressive  way. 12. g2g4 Caruana does not mind the bollocks. 12... c8b7  13. d2e2  13... c5c4 This seems dangerous, but the white pieces are far more  resilient than they seem. 14. d3f5  14... f8e8  15. f3d4 Finally some thought by Caruana. 15... f6d5 Provocation? Or  more likely a blunder? 16. d4e6 The brilliant point behind White's play. All the white pieces  make perfect sense now. Black needs to walk his way through on a very thin road now, on the edge of the abyss. And there is a strong, cold wind  blowing... 16... d8a5 The only move which Duda played after more than  half an hour on the clock. A clear sign that he missed the opponent's last move (or something afterwards). 17. e2f3 Now everything hangs, and nothing can be taken! Let's try to  understand what's happening.