[Event "IBM"]
[Site "Amsterdam"]
[Date "1961.??.??"]
[Round "1"]
[White "Wolthuis, Willem"]
[Black "Tan, Hiong Liong"]
[Result "1/2-1/2"]

1. d4 Nf6 2. c4 e6 3. Nc3 Bb4 4. e3 b6 5. Nf3 Ne4 6. Qc2 Bb7 7. Bd3 f5 8. a3 Bxc3+ 9. bxc3 O-O 10. O-O d6 11. Nd2 Nxd2 12. Bxd2 Qh4 13. f3 Nc6 14. e4 f4 15. c5 dxc5 16. dxc5 Qe7 17. cxb6 axb6 18. a4 Ne5 19. Bb5 Bc6 20. Bxc6 Qc5+ 21. Kh1 Qxc6 22. Rfd1 Ra5 23. c4 Raa8 24. Rdc1 Rfd8 25. Ra3 Qd6 26. Ra2 Nd3 27. Rf1 Rd7 28. h3 Rad8 29. a5 bxa5 30. Bxa5 Nb4 31. Bxb4 Qxb4 32. Rb1 Qxb1+ 33. Qxb1 Rd1+ 34. Qxd1 Rxd1+ 35. Kh2 Rc1 36. Ra6 Rxc4 37. Rxe6 Kf7 38. Re5 g6 39. h4 Kf6 40. Ra5 Rc1 1/2-1/2