Lesson
White to move. Main line: 1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. f3 d5 5. a3 Bxc3+ 6. bxc3 c5 7. cxd5 exd5 8. e3 c4 9. Ne2 Nc6 10. g4 O-O 11. Bg2 Na5 12. O-O Nb3 13. Ra2 b5 14. Ng3 a5 15. g5 Ne8 16. e4 Nxc1 17. Qxc1 Ra6 18. e5 Nc7 19. f4 b4 20. axb4 axb4 21. Rxa6 Nxa6 22. f5 b3 23. Qf4 Nc7 24. f6 g6 25. Qh4 Ne8 26. Qh6 b2 27. Rf4 b1=Q+ 28. Nf1 Qe1
Anand’s Sämisch setup produces a pawn storm with g4, g5, e4 and f4. Carlsen responds on the queenside, creating a protected passer after ...b4 and ...b3 rather than moving defenders toward his king.
White’s f-pawn reaches f6 and the queen reaches h6, creating real mating threats. Meanwhile Black’s b-pawn advances to b2. The position demands exact calculation because each side is one tempo from a decisive breakthrough.
After 27.Rf4, Carlsen promotes with 27...b1=Q+. Anand answered 28.Nf1, but 28...Qe1 ended the game; the intended attack had a tactical flaw. This is a model for analyzing races: checks, promotions and forced replies must be counted before strategic impressions.