[Event "Interzonal-09b"]
[Site "Petropolis"]
[Date "1973.08.07"]
[Round "11"]
[White "Tan, Lian Ann"]
[Black "Biyiasas, Peter"]
[Result "1/2-1/2"]

1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6 4. d4 exd4 5. O-O d6 6. Nxd4 Be7 7. Nc3 O-O 8. Nxc6 bxc6 9. Bf4 Nd7 10. Ne2 Nb6 11. Bd3 c5 12. c4 Bf6 13. Qc2 g6 14. Rab1 a5 15. Rfd1 Qe7 16. Nc3 Bg7 17. Kh1 Bd7 18. Re1 Rfe8 19. Be3 Bc6 20. f3 Be5 21. Qf2 Bxc3 22. bxc3 Bb7 23. Bf4 f6 24. Qg3 Rad8 25. Rb5 Ba6 26. Rxa5 Bxc4 27. Bb1 Ra8 28. Rxa8 Rxa8 29. h4 Bxa2 30. h5 Qf7 31. hxg6 hxg6 32. Bc2 Qh7+ 33. Kg1 Bf7 34. Bc1 Qh5 35. f4 Ra1 36. Bd1 Qh6 37. Bg4 Qg7 38. Kh2 Nc4 39. Bh3 g5 40. Qg4 gxf4 41. Qxf4 Qg5 42. Qxg5+ fxg5 43. Rh1 Ra2 44. Bxg5 Re2 45. Ra1 Rxe4 46. Ra7 Kg7 47. Rxc7 Kg6 48. Be7 Be6 49. Bxe6 Rxe6 50. Bf8 Kf5 51. Rf7+ Ke4 52. Re7 Rxe7 53. Bxe7 Kf5 54. Kh3 Ke6 55. Bh4 Ne5 56. g4 d5 57. Bf2 1/2-1/2