The routine is becoming familiar.
Federico "Kiko" Macheda has done it again. Once was remarkable enough. Twice verges on the incredible.
Aston Villa could count themselves unfortunate to be defeated by a glorious goal. Sunderland were still unluckier, beaten by a strike that contained an element of fortune. Some 46 seconds after his introduction, Macheda positioned himself in the penalty area when Michael Carrick took aim. The ball ended up, via Macheda, in the Sunderland net. The deflection may have contained more luck than judgment, but the result was the same.
"What he knows about it is immaterial," said an admirably phlegmatic Ricky Sbragia. "Everything he touches seems to turn to gold." He was almost right: everything he touches seems to turn to goals.
"He has got something special about him, the boy," said Ferguson. "He is quick thinking. Goalscorers have that. He's got the instinct. He isn't fazed by anything, I have had a chat with his family this week and he will be ok. He will keep his feet on the ground."
That might not be easy. Players can go through an entire career without enjoying a week like Macheda's. Whereas Carlos Tevez had chugged around energetically and Dimitar Berbatov strolled around languidly without either suggesting they would score, Macheda managed it in a matter of seconds. It is now four points that can be attributed solely to the substitute. It is the difference between first and third place. It is scarcely credible.
When Cristiano Ronaldo had been left among the replacements, it appeared he was Ferguson's insurance policy. Events proved Macheda was. If his manager is grateful to the 17-year-old Italian, his team-mates ought to be. For the second successive match, their failings have been obscured by his finishing.
Defensively, once again, United were fragile. There were reasons to rest, or omit, the out-of-form Patrice Evra. Nevertheless, Wednesday's Champions League tie at Porto appeared to have been prioritised with the left-back, alongside Ronaldo, Ryan Giggs and Edwin van der Sar on the bench. It meant Ben Foster was given his first Premier League start of the season and the goalkeeper appeared fallible when failing to claim Teemu Tainio's cross, allowing Kenwyne Jones to equalise at the second attempt.
Nor was it a lone threat. Sunderland may have sensed that their best hope of a result lay, despite a meagre tally of two goals in their six previous games, in attack, and they committed men forward. "All we did today was to try and get the ball into the box as often as possible," said Sbragia. It was a policy that could have brought a reward. Indeed Nemanja Vidic, with a misplaced back-pass, and Jonny Evans, when he touched on Carlos Edwards' cross, both came close to scoring an own goal.
United had begun with purpose. Wayne Rooney had been exiled to the left flank by Ferguson as Dimitar Berbatov returned to partner Carlos Tevez, but he did not interpret it as a slight. Instead, Rooney delivered a terrific display, attempting a shot within 20 seconds and creating a goal within 20 minutes when Paul Scholes headed in his cross.
For much of the season, 1-0 appeared enough for United. Now their games are altogether more unpredictable. But, for the second time in a week, the twist in the tale involved a previously unknown Italian boy. Logically it can't continue, but then logic appeared to have left the title race long before Manchester United's teenage substitute joined it.
MAN OF THE MATCH: Wayne Rooney - Few United players have retained their form in recent weeks. Rooney, however, seems to have improved his. Until Macheda's arrival, he was instrumental in everything United did, tracking back with trademark vigour and serving as creator and, almost, scorer from the left flank.
SUNDERLAND VERDICT: An injury-hit side produced a display of real spirit. The shame for them is that past failings have put them in danger of relegation. "I just question why we didn't get the same performance in the West Ham game," Sbragia said. "We've set ourselves a good standard." There were fine performances across his side, from the overlapping Phil Bardsley to Jones, who ended something of a goal drought, but results are required. Their next match - Hull at home - is huge.
MANCHESTER UNITED VERDICT: They can derive comfort from another victory and the knowledge that three key men - van der Sar, Evra and Giggs - should be rested for the reunion with Porto. Nevertheless, it is hard to name their strongest side at the moment. With each game he misses, Rio Ferdinand's reputation grows higher.
NAUGHTY NEVILLE: With Ronaldo on the bench, his mantle as talisman appeared to have been passed to Rooney. Another of his habits, however, appeared to have been borrowed by his captain. Gary Neville has been called many things in his time, but rarely a diver. This was a rare occasion when he was cautioned for simulation.