It is sometimes said that you are judged by the company you keep. If so, Sunderland should be bathed in the most favourable of lights. Along with Chelsea and Manchester City they are one of only three teams still unbeaten in the Premier League but Martin O'Neill knows that particular statistic flatters his players.

This, after all, was Sunderland's first Premier League win since March and it arrived on a day when an initially promising Wigan fell apart following the dismissal of Jordi Gómez for a naive studs-up tackle on Danny Rose early in the second half. Shortly afterwards Steven Fletcher scored his fifth goal in four league games since joining from Wolves for £12m and his team-mates held on to register a much craved victory.

"We're in big company with Chelsea and Manchester City but it's early, very early," said O'Neill. "I'm just delighted to have got the win." Indeed, without Simon Mignolet around to thwart them, Wigan might have been the side celebrating.

With Roberto Martínez's attractively fluid 3-4-3 formation confusing Sunderland, the Belgium goalkeeper made two stunning first-half saves from James McCarthy and Arouna Koné. "I have to thank Mignolet," said O'Neill. "He's fantastic, really great and a genuinely lovely fella as well, not that matters a hoot as long he keeps the ball out."

To quote their manager, Sunderland were "a bit frayed" but, significantly, the only weak point in their spine was central midfield, where the suspended Lee Cattermole's absence permitted Wigan's McCarthy and James McArthur far too much room for menacing manoeuvre.

Otherwise Mignolet shone, Titus Bramble stood firm against his former employers at centre-half and Fletcher looked the complete centre-forward. Moreover, when the Scot swept James McClean's low cross past Ali al-Habsi at the far post Fletcher did not merely score his fifth goal of the league campaign but also Sunderland's fifth.

"Steven has scored every single Premier League goal for us," said O'Neill. "Just at the moment it isn't a concern but it may well turn into one. We cannot become reliant on a single source."

Heads were shaken when Sunderland paid £12m for Fletcher but their manager was entitled to dub a forward he had long coveted a "bargain" on Saturday evening.

"Of course, you're delighted when someone you sign makes such an impact," said O'Neill. "But I have to say it hasn't really surprised me. I saw Wolves a few times last season and I thought he was a really top quality player."