The transfer most Latics fans were dreading was confirmed just before 11am on Friday morning, after the beat-the-deadline deal was finally ratified by the footballing powers-that-be.
Latics boss Paul Cook had been hoping to keep hold of the player, but accepted all along that ‘every player has his price’.
And tipping point finally arrived just before 10pm on Thursday night.
“This comes with so much emotional attachment because Will is so popular with our supporters and is somebody who has given everyone associated with the club so many great moments,” acknowledged Cook after the deal was announced.
Latics fans had gone to bed on Thursday night/Friday morning facing up to a future without Grigg after Sunderland swooped - after SEVEN failed bids, and for TWENTY TIMES their opening gambit.
Any hope Wiganers had of the deal not being rubber-stamped by the authorities were dashed when Black Cats boss Jack Ross revealed during his 8am media duties that his ‘understanding’ was the deal would go through.
And a social media posting from the Sunderland’s official account showing a flame outside the Academy of Light paved the way for the inevitable.
“It’s well documented we had a bid accepted for Will Grigg very late last night, and my understanding is that it looks like that will all go ahead,” said Ross.
“At the minute we are waiting on FA approval but I’m led to believe that is ok.
“Over the next hour or so we should get confirmation of that.”
Latics did everything to hold on to the Northern Ireland striker, and went into the last couple of hours of the window increasingly confident Grigg would be staying at the DW Stadium.
But in a crazy half-hour, the bidding from Sunderland quickly jumped from £1.5million to £4million - including add-ons - which was reluctantly accepted.
The move wasn’t rubber-stamped by the 11pm deadline, but Sunderland submitted a deal sheet in time.
Grigg becomes one of four departures during a mad 24-hour period, with James Vaughan and Leonardo Da Silva Lopes joining Portsmouth and Gillingham respectively on loan.
Callum Connolly was also recalled by parent club Everton, and joined Bolton for the rest of the campaign.
Everton youngster Beni Baningime - brother of Latics Under-18 star Divin - was the sole arrival, joining on loan until the end of the season.
But a deal for an unnamed free agent - who didn’t have to sign before the deadline - has been put in place and should be completed in the next 24 hours.
Latics did most of their business before the frantic last 24 hours, with defender Danny Fox and forwards Anthony Pilkington and Leon Clarke joining up.
Jamie Walker and Devante Cole also returned to the club midway through their loan deals at Peterborough and Burton respectively.
Jordan Flores (Dundalk) and Alex Bruce (Kilmarnock) moved on to pastures new, with Dan Burn completing a £4million transfer to Brighton.