Arthur Masuaku’s dismissal for spitting summed up a dismal afternoon for West Ham as Will Grigg’s brace continued Wigan’s love affair with the FA Cup.
Masuaku was sent off early in the second half of the Hammers’ 2-0 loss at the DW Stadium when he spat at Latics forward Nick Powell near the side of the pitch.
League One Wigan, winners of the competition in 2013, followed up their elimination of Bournemouth in the third round by ousting another Premier League opponent thanks to goals in either half from Grigg.
Their victory came after visiting boss David Moyes stated he believed Wigan fans would have traded their cup success five years ago for Premier League safety, having been relegated three days after beating Manchester City at Wembley.
He might have reconsidered that view shortly after kick-off as a Wigan side featuring just one change raced out of the blocks in front of a pumped-up crowd.
The hosts lead after just seven minutes from their first attempt on goal as Nathan Byrne’s deep cross from the right was nodded by Grigg beyond Joe Hart and into the top corner.
At such point-blank range, there was little Hart could do but watching England boss Gareth Southgate would have noticed Chey Dunkley squeezed the ball past him moments later too – only for the offside flag to deny Wigan a second.
Obiang immediately indicated he was in some distress and left on a stretcher as Moyes introduced Reece Oxford to the action.
Wigan were well on top but might have been on level terms had Samy Morsy not brilliantly blocked from Javier Hernandez after Antonio Martinez robbed Dan Burn near the byline.
Moyes handed a debut to Joao Mario for the second half the day after he signed on loan from Inter Milan, yet the Hammers were soon down to 10 men.
The flashpoint occurred when Powell challenged Masuaku near the touchline. The former Manchester United forward continued to stare at his West Ham counterpart and as Powell started to walk away Masuaku clearly spat in his direction.
Masuaku did not exit quietly once referee Chris Kavanagh had brandished the red card, with Powell and Grigg involved in heated confrontations as the temperature rose.
West Ham had provided little evidence they would get back into the game and after Grigg flashed a header from a Callum Elder cross wide, Wigan were awarded a penalty to kill the game just after the hour.
It was Grigg who won it when he attempted to flick the ball beyond Burke and appealed for a handball decision that he was granted.
Burke’s arm was bent and tucked in to his body so the offender would have had cause to feel aggrieved.
Nevertheless, the Northern Ireland international slotted his spot-kick straight down the middle while Hart flung himself to his left to double Wigan’s advantage.
The lively Powell should have added a third when Byrne’s cross narrowly evaded him with West Ham, who also lost Martinez to injury, soundly beaten.