And to think that there used to be a song in North London that celebrated the finality of a 1-0 lead when established by Arsenal. These days there is no greater harbinger of chaos.

In the past three weeks, Arsenal have surrendered a single-goal advantage against Chelsea, Liverpool twice and now Manchester United. This fragility has cost them a place in the last four of the Champions League and the league title, conceded by Arsène Wenger after the match.

To their credit, they went down fighting. United will not have to work harder for three points all season and at the end, a rare moment of tenderness between Sir Alex Ferguson and Wenger said much. On occasions it has been a matter of public order to keep them apart; yesterday the United man put a consoling arm around the shoulder of his opposite number after the final whistle and paid tribute to his team in his commentary later.

As a purveyor of the beautiful game, he will respect what Arsenal have set out to achieve this season and will sympathise with the way their pursuit of glory has fallen apart. It is the hardest trick in football to win each week with style, as Ferguson knows; to do so having spent £18.1 million since 2004 (compared with £177.9 million by Chelsea, £100.5 million by Liverpool and £75.3 million by United) is near impossible. Placed in context, Arsenal’s fate should sadden, but not surprise.

That is to take nothing away from United, who showed the depth of resolve that marks out true champions after Emmanuel Adebayor had given Arsenal the lead in the 47th minute with a near-post header from a cross by Robin van Persie. Had Ferguson just thrown money at this team, they would not have found the necessary spirit to come back. More than that, he has been shrewd in his selections, signing players who have the mental strength to match their ability, which is what came to the fore in a stunning second half.

The epitome of this was the poise and self-assurance of Cristiano Ronaldo in getting United level from the penalty spot. It was far from his best afternoon and for long periods he was frustrated by Gaël Clichy, the excellent Arsenal left back. Yet after William Gallas had handled a pass by Michael Carrick – Wenger had his standard moan, but his heart was not in it this time and looking at the replays one can see why – Ronaldo stepped up with the weight of United’s season on his shoulders.

A defeat here would have handed the initiative to Chelsea. Even a draw would have ensured that if the Londoners could win their remaining matches, the title would unexpectedly divert to Stamford Bridge. The pressure was on. Ronaldo checked his run, stopped, sized up the task and stuck the ball out of reach to Jens Lehmann’s right. Unfortunately, while he was playing cat and mouse with the Arsenal goalkeeper, Park Ji Sung had strayed several yards into the area. Howard Webb, the referee, ordered a retake.

The tension mounted. Lehmann was booked for acting like, well, Jens Lehmann. We are familiar with his stupid antics by now. Ronaldo remained unfazed. He checked his run again and found a near-identical spot to Lehmann’s right. Old Trafford erupted.

For Arsenal, this was all too familiar and the rest of the afternoon carried a terrible inevitability, not least after Carlos Tévez had arrived to galvanize United further. Yes, there were chances for the visiting team – a combination of Edwin van der Sar, the United goalkeeper, and the near post kept out a deflection off Wes Brown from a cross by Clichy in the 66th minute and a header by Nicklas Bendtner, a substitute, in the 90th – but between those opportunities United scored the winner, as even those in the travelling section of supporters suspected they would. It was a peach, too, worthy of deciding any match.

Gilberto Silva fouled Patrice Evra, possibly United’s man of the match, although the television award went to Ferdinand, and from the free kick outside the area Owen Hargreaves curled his shot over the Arsenal wall into an unguarded net far to Lehmann’s right.

After all his bravado last week, his boasts of how he would have saved Arsenal in Europe, when finally given a chance in a big game ahead of Manuel Almunia, who injured a wrist in training (perhaps waving goodbye to Lehmann a little too truthfully, considering the state of their relationship), the German proved just as fallible. He did not move for the Hargreaves kick and could barely have been farther from it had he stood by the corner flag. A man on the post would have helped, but hindsight is a beautiful thing.

As at Anfield on Tuesday night, Adebayor missed a good chance one on one that could have made all the difference to the match and had Ferdinand not been saved by Van der Sar from sending the ball into his own net after 50 minutes it would have been hard to see United getting back from two down, but while the difference between the teams stayed at one goal, Arsenal were always vulnerable and will continue to be next season unless Wenger bites the bullet and enters the transfer market.

The decision to play Kolo Touré at right back with the inexperienced Alexandre Song in central defence suggests that Wenger has not been convinced by him since his return from the African Cup of Nations and whatever is argued by Wenger, Gallas has been an unconvincing captain. His soft handball within four minutes of Arsenal’s goal was perhaps the cosmic payback for that showy petulance when Clichy gave away a penalty late in the match against Birmingham City in February. Unlike Clichy’s foul, though, with replays later showing that he had won the ball, Gallas’s infringement was a definite penalty.

Wenger said that his team deserved credit for their contribution to the season and, in that, he was right. They have been great value, great entertainment, poetry in motion at their best and yesterday contributed to the game of the campaign so far, one that might only be matched when United play Chelsea at Stamford Bridge on April 26 with, in all likelihood, the title at stake. Even then it will be hard to match this. These games still represent the high point of the English domestic season, whatever the league table suggests, and Ferguson knows it. That is why he could afford to be generous in victory.

How they rated

Manchester United (4-5-1): E van der Sar 7 W Brown Y 5 R Ferdinand 7 G Piqué 6 P Evra 8 C Ronaldo 6 O Hargreaves 7 M Carrick Y 7 P Scholes 5 Park Ji Sung 5 W Rooney 6 Substitutes: Anderson 6 (for Scholes, 54min), C Tévez 7 (for Park, 54), R Giggs (for Hargreaves, 89). Not used: J O’Shea, T Kuszczak. Next: Blackburn (a).

Arsenal (4-4-1-1): J Lehmann Y 7 K Touré 6 A Song 5 W Gallas Y 6 G Clichy 7 E Eboué 6 C Fàbregas 7 Gilberto 6 R van Persie Y 5 A Hleb Y 7 E Adebayor Y 7 Substitutes: T Walcott 6 (for Eboué, 60min), N Bendtner (for Van Persie, 75), J Hoyte Y (for Touré, 84). Not used: J Djourou, L Fabianski. Next: Reading (h).

Referee: H Webb
Attendance: 75,985

RUN IN

Arsenal Apr 19: Reading (h) Apr 28: Derby County (a) May 3: Everton (h) May 11: Sunderland (a)

Manchester United Apr 19: Blackburn Rovers (a) Apr 26: Chelsea (a) May 3: West Ham United (h) May 11: Wigan Athletic (a)

Chelsea Tonight: Wigan Athletic (h) Apr 17: Everton (a) Apr 26: Manchester United (h) May 3: Newcastle United (a) May 11: Bolton Wanderers (h)