29 November, 2019. Arsenal decide to sack Unai Emery after the club's worst run of results since 1992 and the Gunners go back to the drawing board.
After hiring the Spaniard as a replacement for Arsene Wenger 18 months previously, they'd planned to go with him for the long term. Big signings, including Nicolas Pepe from Lille, were brought in because his judgement was trusted.
But after a 2-1 defeat to Eintracht Frankfurt in the Europa League, Arsenal opted to wield the axe.
Emery, despite being a serial winner following stints at Sevilla and Paris Saint-Germain, was sent packing. The plan, the one they'd had following Wenger's retirement 18 months earlier, was thrown away.
Manchester United and Arsenal will meet at Old Trafford in Sunday's Premier League clash
PA
Arsenal were linked with Patrick Vieira, their former captain.
Massimiliano Allegri was linked with the Gunners as well, while Nuno Espirito Santo saw himself being backed to take over after working wonders at Wolves.
Yet Arsenal, in the end, went with Mikel Arteta.
And, as the old saying goes, the rest is history.
Arsenal's decision to hire Arteta raised eyebrows at the time. While the Spaniard had enjoyed a successful time as a player at the Emirates, some felt the step up for Manchester City's No 2 was far too big.
Not the Gunners board, however.
Explaining the decision to hire Arteta, head of football at the time Raul Sanllehi said: "We met several top-class candidates and Mikel stood out to every single one of us as the perfect person for us.
"Mikel understands Arsenal football club and what it means to our fans around the world.
"We look forward to him getting down to work and bringing the best out of our squad as we work to get our season back on track."
When it came to the 2019/2020 Premier League, it was a season to forget for Arsenal.
They could only finish eighth, with Wolves, Tottenham, Leicester, Chelsea, United, Manchester City and Liverpool all finishing higher.
Yet there was the silver lining of an FA Cup triumph, with Arsenal stunning Chelsea after rocking Manchester City in the last four.
Since then, Arsenal have only got better.
Sure, more trophies must follow. While the Gunners have enjoyed another splendid season, the title seems to be heading to Manchester City once more.
But there's no denying Arsenal have got virtually everything right since Arteta returned to the Emirates with his masterplan, and blueprint for success, consolidated in his mind.
Recruitment under Emery was iffy. Bernd Leno, Kieran Tierney, Pepe and Sokratis Papastathopoulos were never up to scratch.
Arteta didn't just offload the quartet, however. He's signed top talents and players brimming with potential in their places, with Martin Odegaard, Gabriel and Declan Rice among them.
The Spaniard has also stamped his authority on the squad with a set style of play. Arsenal are entertaining to watch, something their league-high total of 88 goals shows.
LATEST SPORTS NEWS:
- Manchester United 'expect Thomas Tuchel talks to progress this week' after Bayern Munich lose to Real Madrid
- Tyson Fury confidence 'has taken a hit' with possible postponement addressed ahead of Oleksandr Usyk fight
- Rory McIlroy makes feelings clear on Tiger Woods relationship 'strain' amid PGA Tour and LIV Golf talks
Arsenal have improved considerably since replacing Unai Emery with Mikel Arteta
GETTY
They will travel to Old Trafford on Sunday as the favourites to emerge victorious, something that long seemed unfathomable.
And it's now time for United to learn from their rivals as they seek a brighter, better future.
The last decade has been tough for the club. David Moyes, Louis van Gaal, Jose Mourinho and Ole Gunnar Solskjaer have all been hired and fired in the years since Sir Alex Ferguson strolled off into the sunset.
United must bite the bullet and sack Erik ten Hag. While he's won one trophy, and could yet claim another, the Dutchman is clearly out of his depth.
Ten Hag's style of play is borderline non-existent and other teams know it. How else can you explain Monday's mauling at the hands of Crystal Palace?
Thomas Tuchel is available, Rubem Amorim is a progressive coach and Gareth Southgate deserves far more respect for the work he's done with England. All three would be upgrades.
Manchester United boss Erik ten Hag seems to be a dead man walking ahead of Sunday's Premier League clash with Arsenal
PA
But United need recruitment to be better, too.
Signing Antony for a fee of £86million is utterly baffling. Spending £60m on the injury-prone Mason Mount is as well. And then there's Casemiro, the 32-year-old veteran whose days at the highest level appear numbered. Giving him a four-year deal, while paying him £350,000-a-week, was always asking for trouble.
Arsenal have moved on by improving off the pitch. They have expertise throughout the club, something United lack.
Sir Jim Ratcliffe is attempting to rectify that but it's early days. The 71-year-old can only be judged once he's had time to truly wave his magic wand.
One thing is certain, however. Arsenal are on the rise - and United are in the middle of a fall.
The Red Devils have lessons to learn. By paying attention to Sunday's opponents, they could yet end their time in the wilderness.
