1. d2d4  1... d7d5  2. c2c4  2... e7e6  3. g1f3  3... d5c4  4. e2e4  4... b7b5  5. a2a4  5... c7c6  6. b1c3 A rare move, but the game will quickly transpose to a well-known position. 6... f8b4 Now we're back to a position with more than a thousand games played. It makes sense for Black to try to exploit White's move order with the move 6...b4. Considering the time spent, it's likely Tan didn't expect this opening and was improvising from this moment on. 7. c1d2  7... d8b6 Another rare move, this time leading to truly unexplored positions already on move eight, something we also saw in the first game of the match. 8. f1e2  8... g8e7 A new move. It makes sense to develop the knight here, to escape from the move e4-e5. 9. d1c2 By protecting the knight, White prepares the thematic break on b3. 9... c8b7  10. b2b3 [%c_effect b3;square;b3;type;GreatFind;persistent;true] 10... c4b3  11. c2b3  11... a7a5 [%c_effect a5;square;a5;type;GreatFind;persistent;true] It's necessary to return the pawn. Exchanging the dark-squared bishop would be positional suicide. 12. a4b5  12... c6b5  13. e2b5  13... b7c6  14. b5d3 Keeping the bishops gives more chances for an advantage. 14... b8d7  15. e1g1  15... e8g8  16. a1b1  16... f8b8 [%c_effect b8;square;b8;type;Mistake;persistent;true] This move puts Black in trouble. 17. d2f4 [%c_effect f4;square;f4;type;GreatFind;persistent;true] This is the problem—the bishop attacks the rook, and White gains precious time to prepare Na2. 17... b8d8  18. c3a2 [%c_effect a2;square;a2;type;GreatFind;persistent;true] This bishop cannot move, and White is much better. 18... d7f6  19. f4g5 [%c_effect g5;square;g5;type;Inaccuracy;persistent;true] 19... a8b8 [%c_effect b8;square;b8;type;Mistake;persistent;true] 20. d4d5 [%c_effect d5;square;d5;type;GreatFind;persistent;true] The thematic central advance is possible thanks to a tactical detail. 20... c6e8  21. b3b2 [%c_effect b2;square;b2;type;Inaccuracy;persistent;true] White has many tempting moves, and it's hard to pick the most accurate. This has always been a flaw in my game: being an indecisive person by nature, I find it difficult to choose just one of several tempting moves. Of course, many other chess players also suffer from this. 21... e7g6  22. f1c1 [%c_effect c1;square;c1;type;Inaccuracy;persistent;true] Again, White has many interesting moves, and this is not the most impressive. 22... h7h6 [%c_effect h6;square;h6;type;GreatFind;persistent;true] 23. g5e3  23... b6b7  24. a2b4  24... a5b4  25. b1a1  25... b8c8 This move is criticized by the computer, although its suggested refutation is not so clear to my eyes. 26. c1c8  26... b7c8  27. b2b4  27... e6d5 