When Arsenal announced that they had reluctantly agreed to sell club captain Robin van Persie to Manchester United in August 2012, it must have felt as if the world had come crashing down for the long-suffering Gunners' faithful.
The man who has scored 30 goals over the course of the 2011/12 campaign had suddenly decided he'd had enough. This hurt more than the Samir Nasri departure, more than the Cesc Fabregas sale, too.
Van Persie was Arsenal through and through. The one star player they thought they could rely on to spend his career at the Emirates Stadium and give 100 per cent every time he pulled on the famous red shirt.
But three months after his final match for Arsenal he would be pulling on a very different red shirt - one belonging to a fierce rival, the most powerful club in England.
The fact that he would go on to win his first Premier League title in his debut season at Old Trafford, scoring against Arsenal in both the home and away fixtures, merely rubbed salt into the raw wounds of the Gunners' supporters.
Van Persie, it seemed, had had the last laugh.
But suddenly things are looking a lot rosier for Arsenal, who currently sit top of the Premier League table after picking up 19 points from their opening eight matches.
Not only that but they also have one of the world's best players in their ranks. Who would have predicted when Van Persie was sold to United that Arsenal would spend £42.4m on world-class playmaker Mesut Ozil 12 months later?
Arsene Wenger's decision to sign Olivier Giroud from Montpellier last summer is also looks like an increasingly shrewd bit of business with each passing week.
The France international is three years younger than Van Persie and isn't a million miles off the Dutchman in terms of quality. In fact, he's come on leaps and bounds over the past year and is now a vital cog in the Arsenal team.
It could even be argued that Giroud is better than Van Persie at bringing his teammates into play - and in an Arsenal side blessed with some of the best midfielders in the world, this is an essential quality for any striker hoping to lead the Gunners' line.
But unlike with Van Persie, the Arsenal players don't constantly feel the need to pick out Giroud in order to score goals or bail them out of a sticky situation.
Wenger's men now operate much better as a team. Sure they lost one of the league's best goalscorers, but this Arsenal side would have wiped the floor with the Arsenal side that contained Van Persie.
The Dutchman isn't getting any younger - and Manchester United will soon need to think about a long-term replacement for the man they forked out £24.5m for just a year ago.
Arsenal, on the other hand, have no such concerns.