[Event "Interzonal-09b"]
[Site "Petropolis"]
[Date "1973.07.28"]
[Round "4"]
[White "Gheorghiu, Florin"]
[Black "Portisch, Lajos"]
[Result "1/2-1/2"]

1. c4 e5 2. Nc3 Nf6 3. Nf3 Nc6 4. g3 Bb4 5. Nd5 Bc5 6. d3 h6 7. Bg2 O-O 8. O-O d6 9. Bd2 Nxd5 10. cxd5 Ne7 11. b4 Bb6 12. a4 a6 13. Qb3 Bd7 14. Bc3 Nf5 15. e4 Ne7 16. d4 f6 17. Nd2 exd4 18. Bb2 Ng6 19. Nf3 d3 20. Qxd3 Ne5 21. Qb3 Nxf3+ 22. Qxf3 Qe7 23. Rfe1 Rae8 24. a5 Ba7 25. Rac1 c6 26. Qd1 1/2-1/2