Andy O'Brien scored his first goal for his country as the Republic of Ireland deservedly beat Portugal.
The victory was inspired by a sparkling performance from Damien Duff, whose trickery and distribution was superb.
O'Brien's first-half winner came from a corner when John O'Shea headed the ball on, the Newcastle defender helped the ball over his line using his knee.
Portugal defender Rogerio Matias hit his own post in the second half as Ireland continued to boss the game.
The indications had been there from the start as Ireland begun brightly, but they were not quite alert enough to take advantage of Portugal's sloppy start.
Spurs' recent acquisition, Andy Reid, collected a wayward pass and charged into the Portuguese penalty area.
But his decision to pass rather than shoot allowed the visitors to escape punishment for squandering possession so poorly.
It served to shake Portugal into life and Cardoso Tiago hit a low shot just past the upright.
Cristiano Ronaldo was next to try his luck but his shot was deflected wide by a number of Irish defenders.
From the resultant corner, Jorge Andrade should have put the visitors ahead but scooped over the bar from six yards out.
Aside from a vicious, swerving free kick by Petit, which was superbly saved by Shay Given, it was the last time Portugal really threatened in the first half.
Defending became their focus as Ireland poured forward, and they were found wanting on the left flank on a number of occasions.
Typically lively and creative, Duff was causing havoc and twice produced crosses for Robbie Keane, who misdirected his headers.
It was from a corner from Portugal's left side that the Republic took the lead as O'Shea headed on and O'Brien nudged the ball over the line with his knee.
Not the prettiest goal, but a memorable one with it being the Newcastle defender's first for his country in his 18 appearances.
Duff came close to doubling his side's advantage when his shot from the edge of the area almost caught out Portugal keeper Ricardo.
Ireland picked up from where they left off after the break, with Duff again pulling all the strings on his 50th international appearance.
He bamboozled two defenders before chipping a teasing cross which caused panic in the Portuguese box.
But Duff was withdrawn on 69 minutes, shortly after picking up a booking for a foul on Ronaldo - the pair had clashed in the first half as rivalries from the Premiership spilled over.
Back in play, Portugal's Matias hit his own post under pressure form Keane as Ireland pushed for a second goal.
Inevitably the match lost its rhythm with so many changes, but Ireland continued to look dangerous.
However, Portugal briefly silenced the crowd when Hugo Viana's shot had Given at full stretch.
His fingertip save pushed the shot around the post and away to safety.
But it was the closest Portugal came to an equaliser as Ireland held on comfortably to extend their unbeaten run to eight matches.
Rep of Ireland: Given, Finnan, Cunningham (Dunne 60), O'Brien, O'Shea, Reid, Holland, Kilbane (Kavanagh 46), Duff (Miller 69), Robbie Keane (McGeady 83), Morrison.
Subs Not Used: Breen, Barrett, Maybury, Kenny, Doherty, Macken, Quinn, Lee, Elliott.
Goals: O'Brien 21.
Portugal: Ricardo, Paulo Ferreira (Viana 46), Andrade, Caneira, Rogerio Matias, Petit, Tiago (Meira 46), Deco (Ricardo Costa 46), Ronaldo (Manuel 70), Simao (Boa Morte 61), Pauleta (Nuno Gomes 46).
Subs Not Used: Quim.
Booked: Rogerio Matias.
Ref: Matthew David Messias (England).