Bad luck or bad prep?

 Round 7 of the 2022 Candidates Tournament saw a strange game between Rapport and Nepomnichtchi. Nepo played a line in the Petroff where Black sacrifices a rook, but draws by perpetual check soon afterwards. However Rapport rejected the first repetition, although this simply forced Nepo to aim for another repetition a few moves later. However, when Rapport avoided the second repetition, he ended up losing his queen for insufficient compensation, with a loss to show for his trouble.

After the game Rapport suggested it was the result of poor preparation, although this move he played was already known to be bad. But not only did this game effect Nepo's standings, it also had an effect on Caruana, who could not believe what he was seeing. Although both Nepo and Caruana won in round 7, the unexpected win for Nepo may have played on Caruan's mind, as he lost to Nakamura in Round 8.

Rapport,Richard (2764) - Nepomniachtchi,Ian (2766) [C42]
FIDE Candidates Tournament chess24.com (7.1), 25.06.2022

1. e4 e5 2. Nf3 Nf6 3. Nxe5 d6 4. Nf3 Nxe4 5. d4 d5 6. Bd3 Bd6 7. O-O O-O 8. c4 c6 9. Qb3 Bg4 10. Bxe4 dxe4 11. Ng5 Be7 12. Nxe4 Qxd4 13. Qxb7 Qxe4 14. Qxa8 Bh3 15. gxh3 Qg6+ 16. Kh1 Qe4+ 17. Kg1 Qg6+ 18. Kh1 Qe4+ 19. f3 Qd3 20. Kg2 Qg6+ 21. Kh1 Qd3 22. Nd2 Qd7 23. Ne4 Na6 24. Qxf8+ Bxf8 25. Bf4 Qxh3 26. Rad1 h6 27. Bg3 Nc5 28. Rfe1 Ne6 29. a3 h5 30. Rd3 Qf5 31. b4 h4 32. Bb8 Ng5 33. Rde3 Nxe4 34. fxe4 Qf2 35. h3 Be7 36. Bh2 Bg5 37. Bg1 Qd2 38. R3e2 Qd3 39. Be3 Bf6 40. Bxa7 Qxh3+ 41. Kg1 Qg3+ 42. Kf1 h3 43. Bg1 Bh4 0-1