Between 17-30 September there are 3 games in Lisbon:
20 Sep - Sporting/Olhanense
Go to http://www.sporting.pt/English/english_home.asp
27 Sep - Benfica/Leixões
Check this websites:
Hope this helps,
Enjoy! about 10 years ago
I would recommend the:
27 Sep - Benfica/Leixões game that Teresa mentioned.
Benfica is in great form. Their last game they won 8 - 1 which is a lot of goals for a soccer match
To buy the tickets you have to go to the stadiums that Teresa has given google map links for. Probably one day in advance would be still ok but the earlier the better.
For the Benfica stadium you can go on the subway to the station called "Colégio Militar/Luz" on the blue metro line about 10 years ago