IT was billed as Roberto v Roberto, but rather more apt would have been David v Goliath.

Roberto Mancini's super-rich Manchester City – backed by Mansour bin Zayed Al Nahyan – against Roberto Martinez's family club, Wigan Athletic – father-figure Dave Whelan et al. It was, indeed, an FA Cup final for those who still view the game through the rosy hue of romanticists' eyes.

Remarkably, there was a fairy-tale ending when substitute Ben Watson headed home the only goal of the game to give little Wigan the trophy for the first time in their 81-year history.

What a fillip as they refocus their attention on their desperate battle to retain their Barclays' Premier League status in their final two league games.

Martinez's men can take great heart from this performance, though having to play Arsenal on Tuesday will undoubtedly be a huge challenge physically after this effort.

City's cerebral pain will last much longer, after losing this final on the back of relinquishing, without a serious fight, the Premier League crown to Manchester United.

Wigan simply tested the resolve and hunger of Mancini's multi-millionaires – who finished the game with 10 men after Pablo Zabaleta was shown two yellow cards in the second half – to breaking point.

City's attempt to put Wigan on the back foot from the outset worked only for nine minutes, by which time Martinez's men in black had shed their stage fright and visibly grown into the challenging role of support act.

There was, of course, a Tartan tinge to their troupe, with former SPL and SFL players Shaun Maloney, James McArthur and James McCarthy all starting, while Gary Caldwell, Fraser Fyvie and Roman Golobart, formerly of Inverness, took their places on the Wigan bench.

However, it was Liverpool-born Callum McManaman who was the pick of Wigan's side, his pace and willingness to drive at opponents causing City problems throughout. The 22-year-old could have made better decisions when twice through in the first half, electing to cut back on both occasions before failing to find the target when eventually he did shoot.

Nevertheless, his willingness to take the game to City acted as an inspiration to those alongside him, and the probing and passing of men such as Maloney, Arouna Kone and McCarthy, along with the overlapping runs of full back Roger Espinoza, ensured City had to remain vigilant.

Espinoza had a claim for a penalty when one of his surging runs ended with the Honduran going down under a challenge from Zabaleta. Referee Andre Mariner was unimpressed as his fall looked theatrical and a tad late, but TV showed there was some merit in the appeal.

City also had a claim for a penalty when Sergio Aguero ran into Antolin Alcaraz, but his claim was made more in hope than conviction.That was a word which City struggled to embrace on the day, appearing to believe something positive would happen for them instead of going out to make it so.

They did create one very good chance on 29 minutes, Sami Nasri cutting in from the left touchline and spotting Aguero's clever run in behind the defence. His low cross found its way to Carlos Tevez, and his low shot back across the diving keeper appeared goal-bound until it struck the trailing right foot of Robles and spun up over the crossbar.

The goalkeeper had Emerson Boyce to thank for deflecting an Aguero near-post shot wide of goal four minutes after the break, as City finally came alive.

The arrival of James Milner for Nasri, and, surprisingly, Jack Rodwell for Tevez underlined Mancini's desperation to try to take a grip of proceedings, but Zabaleta then Matija Nastasic took this too far and were booked for pulling back the still-dangerous McManaman.

There could have been a higher price to pay for the second of these offences, 15 minutes from time, had Maloney's free kick been a fraction lower instead of bouncing on top of Joe Hart's crossbar.

Zabaleta refused to learn from his error, and was shown a second yellow on 84 minutes for bringing down McManaman again. In truth, it could easily have been a straight red. Milner followed him into the book for a similarly-late tackle on Maloney as rattled City tried to regroup.

But they were still in disarray when Maloney sent over his inch-perfect corner for Watson to head home his historic injury-time winner. Mancini's future as City boss must now be under serious threat. Martinez? How could he even think about leaving for Everton after this?