Arsenal's magnificent unbeaten run in the Premiership ended in the pouring rain of Old Trafford with more than a hint of controversy.
The pivotal incident in a game in which animosity often came to the surface and the heroics of endeavour surpassed the delicacy of skill came with 18 minutes left.
As Wayne Rooney and Ryan Giggs exchanged passes on the right side of the Arsenal box, birthday boy Rooney nipped inside and promptly fell to the ground.
Sol Campbell, the nearest Arsenal defender to the United striker had put out his leg to tackle, but it was debateable whether any contact had been made. But referee Mike Riley had other ideas and pointed to the spot.
Memories of another penalty, just over a year before on the same ground, between the same teams, but at the opposite end to the West Stand flooded back.
Then Ruud van Nistelrooy had stepped up deep into injury-time of a goalless game to send his kick crashing against the bar with Arsenal goalkeeper Jens Lehmann beaten.
It prompted disgraceful scenes as van Nistelrooy was goaded and pushed and ramifications which lasted many months as Arsenal were heavily fined as a club and some of their players received suspensions.
This time the reaction was more of controlled anger, but amid this van Nistelrooy kept his cool.
He placed the ball on the spot, strode forward and struck his penalty right footed into the bottom right corner of the net with the dancing Lehmann going in the opposite direction.
There was still a way back for Arsenal, but United braced themselves and the Red line held.
Then, almost three minutes into injury time, Louis Saha, who had replaced van Nistelrooy seconds before, found fellow substitute Alan Smith on the right side of the Arsenal box.
Smith rolled the ball across the penalty area to the unmarked Rooney and he gave himself the perfect present for his 19th birthday when he tapped the ball beyond Lehmann and into the net from ten yards.
So, a half century of unbeaten games in the Premiership was not to be, but 49 matches without defeat still remains a tremendous achievement.
It was almost as if the gods had predestined it to end on a passion filled Sunday afternoon against bitter rivals United at Old Trafford.
In truth, Arsenal seldom maintained that high level of consistency which has become a benchmark for their greatness.
United goalkeeper Roy Carroll had only one serious save to make in the game and that came three minutes from the end of a lively and even first half.
Edu's glorious throughball found Thierry Henry ghosting in on the right hand side of the United box and his crisp low shot from eight yards was well saved by Carroll with his feet at the near post.
United's best chance of the first period was a double effort in the seventh minute.
A Gabriel Heinze cross from the left found Rooney on the left side of the Arsenal box. His shot was blocked by Kolo Toure but the ball was only hacked as far as Paul Scholes just outside the penalty area.
Scholes gave it back to Rooney who worked it inside to Giggs, but his goalbound shot was bravely blocked by Campbell.
United could have had Rio Ferdinand sent off in the first half when he bundled over Freddie Ljungberg two yards outside the United box.
Ljungberg was through and Ferdinand the last defender, but Mr Riley waved play on.
Arsenal may be eight points clear of United, but at least the result proves to the rest of the Premiership that they are not infallible.