Ferguson's statement of intent loud and clear

When a rivalry is as deeply scored as that between Sherlock Holmes and Moriarty, such a triumph is satisfying, indeed, for the victor. But for Sir Alex Ferguson, this humiliation of his most resourceful and begrudgingly respected opponent was a reminder that, on all fronts, United are unbowed by recent events. Although this was a welcome respite from Premier League endeavours, supremacy in that competition is never far from the Scot's mind.

Having seen his team claim one point from the last six available, he declared in his match programme notes that yesterday's fifth-round tie was "a speedy and ideal opportunity to make it clear that the emergence of the Gunners with a five-point lead at the top of the table may not be as decisive as some folk are assuming".

You could be certain Arsène Wenger would take a rather contrary view to his nemesis; in part, because they simply do. It's in their DNAs. Yet, however he chooses to analyse this facile triumph by United, no matter his mitigation that the Champions' League holders Milan await his side on Wednesday, and that several members of his team were absent with injuries, the Frenchman would not have wanted to exit the Cup in this craven manner. Though Nani's showboating late on earned the displeasure of Wenger, who regarded it "disrespectful", and even Ferguson – "he shouldn't be doing that" – it was a cruel indicator of United's disdain for the opposition.

Arsenal's elimination, following their non-appearance in next Sunday's Carling Cup final, the consequence of a hefty defeat by Spurs, certainly removes a distraction from their League and European endeavours.

"When we lose in cups we get a hiding," Wenger said, trying to make light of things. "We don't concede many goals, but when we do, we do it well." His counterpart would prefer to believe that this could have a significant effect on the balance of power. "I do hope so," said Ferguson. "When Arsenal come back here [in the League, in just under two months' time], they know they're going to have a real game."

Arsenal kept United waiting after half-time, at 3-0 down, and presumably they would have preferred it if referee Alan Wiley had stopped the contest then. When Emmanuel Eboué was dismissed for a 49th-minute challenge on Nani it was a question of damage limitation.

Despite that sending-off, there were never quite the confrontational excesses of certain meetings that one can recall, including that disgraceful day, 21 September 2003, when, under the captaincies of Patrick Vieira and Roy Keane, it concluded with an Arsenal lynch mob haranguing Ruud van Nistelrooy.

It is worth mentioning it was in that same month that Cesc Fabregas joined Arsenal and became the club's youngest-ever first-team player as a 16-year-old. How the Spaniard has influenced Arsenal's fortunes in the intervening period. Here, he could exert no authority, unlike the impressive Michael Carrick, under the gaze of the England manager, Fabio Capello.

It was an evening for United's less-heralded performers. Cristiano Ronaldo had the evening off, Carlos Tevez was restricted to the bench, as was Paul Scholes, who did get a run-out. The visitors were seriously depleted. By the time first-choice personnel Emmanuel Adebayor and Mathieu Flamini entered the fray the game had long gone.

Indecision in the Gunners' rearguard cost them dear when Wayne Rooney did something he had not for nearly a month for club and country. He scored. Darren Fletcher did the same; something he hadn't achieved all season. Nani's superb take and strike across Jens Lehmann was excellent finishing, but exposed the Arsenal defence once more. At the final whistle, Old Trafford rose to acclaim a famous victory. Maybe that will be as good as it gets for them this season, certainly where the title is concerned. Or is this just the impetus United needed?