[Event "Olympiad-19 Preliminaries A"]
[Site "Siegen"]
[Date "1970.09.05"]
[Round "1"]
[White "Olsen, Henry"]
[Black "Yabra, Frederico"]
[Result "1/2-1/2"]
1. d4 Nf6 2. c4 e5 3. dxe5 Ne4 4. Nf3 Nc6 5. g3 Bc5 6. e3 Qe7 7. Bg2 Bb4+ 8. Nbd2 Nxe5 9. O-O Nxd2 10. Bxd2 Bxd2 11. Qxd2 Nxf3+ 12. Bxf3 d6 13. Rfd1 O-O 14. Qe2 Rb8 15. Bg2 Bd7 16. Qc2 Rfe8 17. Rd4 g6 18. Rad1 Bc6 19. e4 Qf6 20. b4 a6 21. a4 Re7 22. b5 Be8 23. c5 axb5 24. cxd6 cxd6 25. Rxd6 Re6 26. Rxe6 Qxe6 27. axb5 Bxb5 28. Qc7 Qe8 29. e5 Ba4 30. Re1 Bc6 31. e6 fxe6 32. Rxe6 Qxe6 33. Qxb8+ Kg7 34. Qc7+ Qf7 35. Qe5+ Qf6 36. Qc7+ Kh6 37. Bxc6 bxc6 38. Kf1 Qe6 39. Qf4+ Kg7 40. Qd4+ 1/2-1/2