Manchester City 1 Wigan 2: Manchester City have all the billions in the world but they cannot rid themselves of Wigan Athletic. Once again, against all the odds, against all available logic, they have stunned City in the FA Cup. A semi-final against Arsenal is theirs. The FA Cup is still theirs. The holders are still standing. How do they do it? Wigan, bloody hell.

Last year it was the final and Ben Watson’s crazy last-minute winner, but this was just as remarkable. This time it was a quarter-final at Fortress Etihad, where no one, probably not even Wigan, truly expected lightning to strike twice.

Yet goals in both halves from Jordi Gómez and James Perch gave them something to defend and then, in the face of a late City onslaught, they simply would not budge, throwing heart, body, soul and anything else they could find to hold on to a famous victory. For their manager, Uwe Rösler, the former City striker, it is undoubtedly the greatest result of his career.

There could be no excuses for City, who are painfully aware that Wigan are underdogs who would snap away at their heels and who could deliver a potent bite if they were not kept on a tight lead.

Yet City had already exorcised their Wembley ghosts by winning last Sunday’s Capital One Cup final against Sunderland – they paraded the trophy before kick-off – and they could be forgiven for not being too afraid of Wigan given that they beat them 5-0 in the third round of that competition in September.

Yet a lot has changed for Wigan since that thrashing. Not only were they worn down by the demands of the Europa League, they were also managed by Owen Coyle, whose ill-fated reign was hastily ended in December.

His replacement was Rösler, whose impressive work at Brentford in League One had won him plenty of admirers. This was an emotional afternoon for the German. Rösler spent four years at City in the mid-90s, named his son Colin, after Colin Bell, and was inducted into club's Hall of Fame by supporters. For Rösler, the challenge was not to allow the occasion to become about him.

Judging by the fearless way Wigan went about their task, there was no chance of that happening. Rösler, who has lifted them to seventh place, caught City by surprise by setting up his side in a 5-3-2 formation that allowed them to squeeze the space and dominate midfield, while retaining a threat in attack, where the hyperactive Callum McManaman was a constant blur of motion. Just as it was at Wembley 10 months ago, the City defence was often at the mercy of the winger’s speed, skill and directness.

City, with more than one eye on the second leg of their last-16 Champions League tie against Barcelona on Wednesday, were rattled by Wigan’s effervescence.

Yet although Manuel Pellegrini rested Joe Hart, Vincent Kompany, Pablo Zabaleta, Fernandinho and David Silva, City's bedraggled state was startling. They did not have a shot on target until the 66th minute and frustration at their own inertia was summed up when Samir Nasri was booked for dissent for kicking the ball away during a first half in which City did not threaten once.

Wigan, playing with verve and tenacity, fancied themselves against a rocky City defence in which Martin Demichelis was a disaster waiting to happen. For a club of City's vast resources, it is staggering that they are forced to rely on a player who always looks to be on the verge of calamity and it was hardly a surprise that he was at fault when Wigan took the lead.

Rolled far too easily by Marc-Antoine Fortuné, Demichelis compounded his error responded by standing on the striker’s foot to concede a penalty after 28 minutes. In the absence of the injured Watson, Gomez stepped up to send Costel Pantilimon the wrong way.

It was happening again. Wigan, little old Wigan, were doing it again but surely even they could not have dreamt that they would double their lead a minute into the second half. Once again, City’s defending was clownish.

James McArthur drove into the area on the left and pulled a low cross towards the far post, where the horribly timid Gaël Clichy allowed Perch to bundle the ball past Pantilimon.

Pellegrini demonstrated his displeasure by making three substitutions after 53 minutes, replacing Yaya Touré, Álvaro Negredo and Jesús Navas with Silva, Edin Dzeko and James Milner.

Wigan were starting to tire and the more they retreated, the more likely a City goal became. Sure enough, Nasri restored hope when his belting shot from the edge of the area went through the bodies and into the bottom left corner. However it was debatable whether the goal should have stood as Dzeko was offside and arguably blocking Scott Carson’s view.

Nonetheless there were 23 minutes left for Wigan to hold on and soon Micah Richards was curling inches wide. Then, with 10 minutes left, Emmerson Boyce extraordinarily turned Milner's cross over his own bar with Dzeko waiting to tap home. A minute later, Carson saved from Sergio Agüero. Then, as Carson stood still, Dzeko headed wide. Surely Wigan could not hold on. Surely City would score a second, then a third. But that's what we thought last May.

FA semi-final draw: Hull v Sheffield United; Wigan v Arsenal.

Ties will take place at Wembley on Saturday, April 12th and Sunday, April 13th.

(Guardian Service)