[Event "Hoogovens"]
[Site "Wijk aan Zee"]
[Date "1972.01.24"]
[Round "11"]
[White "Portisch, Lajos"]
[Black "Donner, Jan Hein"]
[Result "1/2-1/2"]

1. c4 c6 2. e4 e5 3. Nf3 d6 4. d4 Nd7 5. Nc3 g6 6. Be2 Bg7 7. O-O Ngf6 8. Re1 O-O 9. Rb1 Re8 10. Bf1 a5 11. b3 Qc7 12. d5 Nc5 13. Nd2 Bd7 14. a3 Reb8 15. b4 axb4 16. axb4 Na6 17. Na2 Rd8 18. Nb3 c5 19. b5 Nb8 20. Nc3 Be8 21. Bd2 Nbd7 22. Ra1 Rxa1 23. Qxa1 Nb6 24. Na4 Nbd7 25. Nb2 Rb8 26. Nd3 1/2-1/2