Dyer was up-ended on the left after some impressive work, and from the resulting free-kick, provided on-loan centre back Helder with his first goal for the club.
Elsewhere, an historic night for Cristiano Ronaldo -- who was winning his 100th cap for Portugal -- was upstaged by visitors Northern Ireland , who led for large parts of the game in Porto before Helder Postiga earned a 1-1 draw just ten minutes from time.