"Sensational," said the Republic of Ireland's manager, Brian Kerr who, like everyone else, is running out of superlatives for the 25-year-old. Sensational would also describe Kerr's record. This was some scalp to add to the Netherlands and Czech Republic and clean sheets against Brazil and France. Just two defeats in 25 games, just one goal in six and 10 shut-outs in 14 in repelling Portugal who had scored 20 times in five matches.
Duff's performance was witnessed by his Chelsea manager, Jose Mourinho, who must of winced at some of the tackles inflicted on his player who, it appeared, was intent on challenging his boss's claim that Paulo Ferreira is the world's best right-back. Ferreira lasted 45 minutes as did the impressive Tiago. Indeed, the whole Portuguese team was impressive, better than Brazil, Kerr claimed. "I thought they were excellent," he said, "the best team to play here since maybe the last time Portugal did." That was 2001 and in the last World Cup qualifiers.
Portugal will undoubtedly be in Germany next year as well and their manager, Luiz Felipe Scolari, said that facing Ireland presented his players with the "physical challenge" they do not usually face. That was a harsh assessment although when, on four minutes, Duff squared up to Cristiano Ronaldo it was an arresting sight. The Portuguese had the better of the opening, but suddenly Ireland shifted through the gears. And it was Duff's foot on the pedal.
He collected Clinton Morrison's tidy work, tore down the right, checked back and crossed for Robbie Keane to make a hash of his header. No matter, he thrust forward again and as Kevin Kilbane broke into the box he was pulled down. A corner was given instead of a penalty. But from it Kilbane headed on and Andy O'Brien stabbed home his first goal in his 18th international match.
Portugal came back. Ronaldo worked through his tricks - nutmegging Duff - but the Irishman was having none of it. He feinted, jinked, beat two men and again teed up Keane. The ball was whisked from his toe. That was in the second half and Portugal quickly rang through their substitutions. Their challenge faltered and Keane harrassed Ricardo Costa into poking the ball against his own post while the clever Andy Reid, after a brilliant touchline dribble, dragged shots. Duff even got himself booked for tripping Ronaldo.
Portugal continued to dominate possession, however, and a shot by Hugo Viana appeared to have beaten Given. Instead it billowed the outside of the net. At the end Scolari said the result did not matter. What did, he said, was the experience. It was a tough one. Would he want Duff in the Portuguese side? "He's Irish," Scolari noted. And Dublin rejoiced at that.
REPUBLIC OF IRELAND (4-4-2): Given (Newcastle United); Finnan (Liverpool), Cunningham (Birmingham City), O'Brien (Newcastle), O'Shea (Manchester United); Duff (Chelsea), Holland (Charlton Athletic), Kilbane (Everton), Reid (Tottenham Hotspur); Morrison (Birmingham), Keane (Tottenham Hotspur). Substitutes: Kavanagh (Cardiff City) for Kilbane, h-t; Dunne (Manchester City) for Cunningham, 59; Miller (Manchester United) for Duff, 69; McGeady (Celtic) for Keane, 83.
PORTUGAL (4-2-1-2-1): Ricardo (Sporting Lisbon); Ferreira (Chelsea), Andrade (Deportivo La Coruna), Caneira (Valencia), Rogerio Matias (Vitoria); Petit (Benfica), Tiago (Chelsea); Deco (Barcelona); Ronaldo (Manchester United), Simao (Benfica); Pauleta (Paris St Germain). Substitutes: Viana (Sporting Lisbon) for Ferreira, h-t; Nuno Gomes (Benfica) for Pauleta, h-t; Meira (VFB Stuttgart) for Tiago, h-t; R Costa (Porto) for Deco, h- t; Boa Morte (Fulham) for Simao, 61; Fernandes (Benfica) for Ronaldo, 70.
Referee: M Messias (England)