As a boy growing up in Cork, Stephen Ireland dreamt of emulating his hero, Roy Keane, the man whose posters adorned his bedroom wall. It is a guilty secret for someone who now plies his trade with Manchester City, but the 21-year-old midfield player showed his true colours in the most unexpected manner last night, marking his decisive goal against Keane’s Sunderland by dropping his shorts to reveal a rather dubious pair of sky blue pants, complete with Superman logo.

It is a celebration that is unlikely to cause any great mirth among those fun-loving types in the FA disciplinary department, who fined Joey Barton, Ireland’s former City teammate, for showing only a little more cheek towards Everton supporters last season. After a troubled few months, in which he earned a severe reprimand from Sven-Göran Eriksson for citing imaginary deaths in the family to pull out of one of Ireland’s European Championship qualifying matches, the youngster could certainly do without any more adverse publicity.

Eriksson, the City manager, knows more than most about the machinations at Soho Square, having spent 5½ years as England head coach, and he suggested that the Ireland incident should not merit a disciplinary charge from the governing body. “Maybe, but I hope not,” he said. “I just want to comment on the great goal he scored and hope for the best with the rest. It was a super goal – Superman for a super goal.”

It was indeed a fine strike, Ireland scoring with a perfectly timed volley at the far post midway through the second half after Darius Vassell, the substitute, wriggled free of Nyron Nosworthy to cross. The goal elevated City back up to third place in the Barclays Premier League after their 6-0 drubbing at Stamford Bridge and, to put it in a historical context, it is the first time since 1902 that they have won their first seven home matches in all competitions, even if it was overshadowed slightly by an aggravation of Michael Johnson’s groin problem and news of a similar injury suffered in training by Nedum Onuoha. Johnson will require surgery sooner rather than later and a three-week layoff.

There is little, though, that can wipe the smile off Eriksson’s face at present, even if this was probably their worst performance at the City of Manchester Stadium this season.

It was a rare moment of quality that won it, but, however harsh the scoreline might have been on Sunderland, who were the better team for much of the game, Keane said it was a lesson learnt, rather than a hard-luck story.

“No,” he said when asked if he felt his players deserved better. “We didn’t do enough in the final third. Maybe they didn’t either, but they scored. They produced that one bit of quality that was the difference.” It is becoming a familiar lament for Keane, which is probably one reason why he was unwilling to talk of misfortune. “I think it’s a great example of where we’re short,” he said.

“I could sit here and bore you to death. I said the same a couple of weeks ago at West Ham, when we lost 3-1. I look at other managers of teams at the bottom and they keep saying: ‘We’re playing OK.’ Yes, we are too, but we’re losing football matches.”

With a solitary win since the opening day of the campaign, Sunderland are certainly not going into Saturday’s lunchtime derby match at home to Newcastle United in peak form, but this could have been a different kind of evening. They were certainly the better team for the first half-hour, with Anthony Stokes unfortunate to miss with a towering header from Grant Leadbitter’s cross. That was about the only chance of note in the first half, save for a shot by Emile Mpenza that flew wide of the near post after a typically slick exchange between Ireland and Elano.

A stalemate seemed inevitable, but then Vassell, on for the injured Johnson, picked up a crossfield pass from Martin Petrov, beat Nosworthy and crossed to set up Ireland, who had the time and space to send a crisp volley past Craig Gordon for his first goal of the season.

There followed the season’s most bizarre goal celebration to date, of which Keane, it is fair to assume, did not see the funny side. Revelling in the misery of the former Manchester United captain, having jeered him throughout, City’s supporters spent the final moments chanting: “Keano, Keano, what’s the score?” And no, he did not find that funny, either.

Manchester City (4-2-3-1): J Hart – Sun Jihai, V Corluka, R Dunne, J Garrido – D Hamann, M Johnson (sub: D Vassell, 46min) – S Ireland, Elano (sub: M Ball, 82), M Petrov – E Mpenza (sub: R Bianchi, 57). Substitutes not used: A Isaksson, Geovanni.

Sunderland (4-4-2): C Gordon - N Nosworthy, D Collins, D Higginbotham, I Harte – G Leadbitter, D Etuhu, L Miller, D Murphy (sub: R Wallace, 58) – K Jones, A Stokes (sub: M Chopra, 58). Substitutes not used: D Ward, G Kavanagh, D Connolly. Booked: Nosworthy.

Referee: A Wiley.