[Event "Interzonal-09b"]
[Site "Petropolis"]
[Date "1973.07.24"]
[Round "1"]
[White "Portisch, Lajos"]
[Black "Keres, Paul"]
[Result "1-0"]

1. c4 Nf6 2. Nc3 e6 3. Nf3 c5 4. g3 d5 5. cxd5 Nxd5 6. Bg2 Be7 7. O-O O-O 8. d4 Nc6 9. Nxd5 exd5 10. Be3 Bf6 11. dxc5 Bxb2 12. Rb1 Bf6 13. Ne1 d4 14. Bf4 Qa5 15. Nd3 Qxa2 16. Bd6 Re8 17. Nf4 Bf5 18. Rxb7 Be4 19. Bxe4 Rxe4 20. Qb1 Qxb1 21. Rfxb1 Ree8 22. Rc7 Rec8 23. Rbb7 Rxc7 24. Rxc7 Na5 25. Nd5 Bd8 26. Ne7+ Bxe7 27. Bxe7 h6 28. c6 Rb8 29. Bd6 Kh7 30. Rxf7 Rb1+ 31. Kg2 Nxc6 32. Rc7 Nd8 33. Rxa7 Rb5 34. f4 Nb7 35. Be5 Rb4 36. Bxd4 g5 37. Kf3 Kg6 38. Ra6+ Kf7 39. e3 1-0