Magnus Carlsen started the World Cup with 4 from 4, befitting his number 1 seeding. However the first game of the third round didn't go according to plan, as he got hacked by Xiangzhi Bu from China. Carlsen played the Bishops Opening, and Bu sensibly played the Black side like a Ruy Lopez. He even went as far as playing a Marshall Gambit type sacrifice, and after Carlsen accepted, went nuts on king side. Carlsen could have taken an immediate draw after the sacrifice on h3, but decided to play for a win instead. However this blew up in his face, not so much because of his position, but that he spent so much time working out what to do. As a result, he got into severe time trouble and played a couple of second best moves. Bu gave him one chance at the end, but after Carlsen missed it, the upset was on the scoreboard.
In other weird news, Anton Kovalyov (CAN) walked out of the tournament after getting into an argument with the organisers over his choice of attire. He had worn shorts for the first two rounds, but was told that this was unacceptable just before the third round was due to start. He then exchanged words with tournament organiser Zurab Azmaiparashvili, was apparently called a 'gypsy', and then left. Normally he may have decided to appeal to the FIDE appointed appeals committee over Azmai's actions, but FIDE appointed Azmai as the chairman of the appeals committee, so that option seemed pointless. (As an aside, being on a FIDE appeals committee is a sweet gig, and is used as part of the FIDE reward and patronage system, so Azmai's appointment makes sense, but only from that point of view)
Carlsen,Magnus (2822) - Bu,Xiangzhi (2710) [C55]
FIDE World Cup 2017 Tbilisi GEO (3.1), 09.09.2017
1. e4 e5 2. Bc4 Nf6 3. d3 Nc6 4. Nf3 Be7 5. O-O O-O 6. Bb3 d6 7. c3 Be6 8. Re1 Qd7 9. Nbd2 Rab8 10. Bc2 d5 11. h3 h6 12. exd5 Nxd5 13. Nxe5 Nxe5 14. Rxe5 Bd6 15. Re1 Bxh3 16. gxh3 Qxh3 17. Nf1 Rbe8 18. d4 f5 19. Bb3 c6 20. f4 Kh7 21. Bxd5 cxd5 22. Re3 Rxe3 23. Bxe3 g5 24. Kf2 gxf4 25. Qf3 fxe3+ 26. Nxe3 Qh2+ 27. Kf1 Rg8 28. Qxf5+ Rg6 29. Ke1 h5 30. Kd1 Kh6 31. Nc2 h4 32. Ne1 h3 33. Nf3 Qg2 34. Ne1 Qg4+ 35. Qxg4 Rxg4 36. Nf3 Rg1+ 37. Nxg1 h2 0-1