context: 1. a1b3 Interestingly, in this starting position the weakest square is a2-a7, which has no protection. In the conventional chess position the weakest point is f2-f7, which at least has the protection of the king. The move 1.f4 therefore creates an immediate threat right after the first move. 1.Nb3 brings the knight into play and protects the weakness on a2. This move was played in all the games of the round. 1... d8c6 There are many alternatives. The opening theory in each position of Freestyle allows for many hours of discoveries. 2. e2e4  2... e7e5  3. f2f3  3... f7f6  4. d1c3  4... a8b6  5. c1b1 The moves by both players up to this point were very logical. Firouzja, needing a win, decides to spice things up a little. 5... f8b4  6. e1g3  6... e8e7  7. c3b5 This looks like a strange move to me, but the computer doesn't consider it wrong. 7... a7a6  8. b5c3 By going up and down with the knight, the b6-square has been weakened and I think this was Keymer's plan. He now can consider capturing on b6 in a better version, but Firouzja also has some ideas. 8... b4c3  9. d2c3  9... b6a4  10. g1e3  10... b7b5 An excellent move. More than going for b5-b4, which can be met by c3-c4, Firouzja secures the c4-square for the bishop. 11. f3f4  11... g8c4  12. g3g4 This allows Black to capture on f4. 12... e5f4 