They spent much of the afternoon stumbling rather than strutting yet, by the end of it, Sunderland had won a Premier League game for the first time since March. With Martin O'Neill's team unbeaten this season, the final whistle signalled that the Northern Irishman's glass will be regarded as half full, but for much of the first hour his players looked to be running on empty.

Everything changed early in the second half when Jordi Gómez was sent off and, as Wigan struggled to adapt, Steven Fletcher continued to make his once apparently rather steep £12m transfer fee appear a bargain by scoring the winner. It was Fletcher's fifth goal since arriving from Wolves in the summer.

While the Scottish centre-forward is already a cult hero on Wearside the home goalkeeper rightly enjoyed a mini ovation at the end. Simon Mignolet faces a strong challenge from the Republic of Ireland's Keiren Westwood for the first choice goalkeeper's jersey but the Belgian did not take long to demonstrate why he remains O'Neill's preferred option. When Jean Beausejour's cross was met by Arouna Koné's outstretched boot at close range only Mignolet's brilliant diving save came between Wigan and an early lead.

Despite Adam Johnson's eagerly awaited return from a thigh injury, Sunderland started in scrappy, slapdash mode. Although Iván Ramis was required to clear off the line following a Sebastian Larsson free-kick, Roberto Martínez's fluid, flexible, 3-4-3 formation appeared to be flummoxing O'Neill's players.

Without the much-missed Lee Cattermole around to break up their attacks – Sunderland's captain, a former Wigan midfielder, was suspended again – the visitors found themselves able to weave passing patterns. Indeed they might have scored shortly before half time had James McCarthy – who along with James McArthur controlled midfield – not sent his shot wide of an upright.

Earlier Mignolet had reacted smartly to repel a McCarthy drive with his feet but O'Neill must have been frustrated with his side's failure to test Ali al-Habsi's reflexes. Granted, Fletcher directed a header wide but, with Johnson seeing too little of the ball to make his presence felt, it was all too easy to understand why Sunderland had gone so long without a League victory.

No matter; Gómez and Howard Webb combined to offer their hosts a little help, the referee showing the Wigan forward a straight red card for a studs-up tackle on Danny Rose.

Webb was adhering to the letter of the law but, although reckless, it was the sort of challenge which sometimes receives a yellow. ''The sending off changed things," Martínez said. "I thought we'd started really well and I could only see Sunderland being a threat from a dead ball situation. In the end they had one shot on target and collected three points.

''I think the sending-off was harsh because Danny Rose loses the ball slightly, Jordi Gómez tackles like a striker showing his studs but he doesn't leave the ground. I understand the reason the referee gave it but Sunderland's Larsson later made a worse challenge and he was only shown a yellow."

Stéphane Sessègnon and James McClean were disappointing – (the latter proving fortunate to escape a booking until late on) – but Sessègnon's clever pass and McClean's left wing cross prefaced Fletcher sweeping a first time shot beyond Habsi.

"The win was vitally important and I want to thank Mignolet for a couple of incredibly good saves," O'Neill said. "It was edgy but Steven Fletcher was brilliant; he's looking a bargain."