Manchester United have this psychological hold on Arsenal at the moment, that the current leaders of the English Premier League just cannot escape from.
Sunday was the moment for Arsenal to finally unshackle themselves from United, without that great man Sir Alex Ferguson, and send them a message, like United have so often done to Arsene Wenger's men.
With not much to lose, Arsenal could play freely, and "have some fun" as Mesut Ozil said prior to the game. But, far from fun it turned out to be, as United came out of the blocks much quicker with the Gunners' arsenal left behind in north London.
Manchester United vs Arsenal at the moment is a bit like Rafael Nadal vs Roger Federer. Federer, as much as he tries, cannot seem to get the better of Nadal, and the same can be said of Arsenal, when it comes to facing United.
Two out of the three times that Arsenal have won at Old Trafford under Wenger, they have gone on to win the Premier League title. That is not to say that the Gunners will now not win the league this season; but an 11-point lead over United would have certainly put one rival firmly planted behind the 8-ball.
An Arsenal side, with a winning habit, would have won at Old Trafford, or at the very least come away with a point. However, it was the home side, well versed with winning things in the recent past, that came up trumps, on the back of a good first half performance.
Moyes would have been a little wary of Wenger and his band of exciting-football-men coming to Old Trafford and playing without any fear. However, despite the considerably large shadow of Sir Alex Ferguson firmly planted in the director's box for the match, Arsenal failed to show up.
This was not a game for Arsenal to be resilient in defence and hit the home team on the counter; it was a game to be taken by the scruff of the neck from minute one and never relinquished until the final whistle.
That psychological edge, and the scars of that 8-2 defeat a couple of years ago, however, won over. United were stronger, more determined and deservedly got the opening goal, before holding off an all-too-late Arsenal figthback.
It was not a surprise that the man who bulged the net was Robin Van Persie, who seems to love scoring against his former side - the folly of selling the Dutchman just keeps coming back to bite Arsenal time and again.
The Gunners should have kept Van Persie at the Emirates last season and made his see out his contract - if he left on a free transfer earlier this summer, so be it. Look at what Dortmund have done with Robert Lewandowski. You do not sell your best player to a direct rival, period - yes football is a business, and in business you never ever strengthen a rival.
And who knows, maybe Van Persie would have even extended his contract at Arsenal after seeing the likes of Mesut Ozil make their way to the Emirates.
But then, that thought is for another day. The reality is Van Persie proved to be the match-winner for Manchester United, with his "sidekick" -- Wayne Rooney -- as Moyes put it, putting in a man of the match performance.
While Didier Drogba has come to haunt Arsenal a few times over the years, Arsenal will be equally, if not more, sick of the sight of Rooney. The United frontman just seems to raise his game when up against Wenger and co., and was head and shoulders above Arsenal's famed playmakers.
Mesut Ozil, Aaron Ramsey, Santi Cazorla will all have better days; but on Sunday, it was Rooney and Manchester United, once again, that came away with the spoils, leaving Arsenal wondering, and wishing, if only....
