The finish was sublime, and Nani's through-pass very nice indeed. Any striker would have appreciated it. Yet not any striker would have thought as clearly as Rooney as it arrived at his feet and Christian Abbiati, the AC Milan goalkeeper, advanced.
He had many choices at that moment. To get the ball under control and try to take it on and around was the favourite. To strike his shot as hard and as quickly as possible on the half-volley from range was another option, the drawback being that snatching at his chance could force it wide.
So Rooney did neither. He is making all the right moves now, all the right choices, and he knocked the ball, with the outside of his boot, in the precise place Abbiati was least expecting it: the inside. The finish was both understated and audacious, because it afforded the slightest touch.
The finished article: Wayne Rooney caresses his second of the night past the advancing Christian Abbiati
Yet Rooney executed it so deftly, so sweetly, that there was never a hope of running it down on its way into goal. Within 30 minutes the news had filtered through that Lyon had equalised and Real Madrid, and Cristiano Ronaldo, were on their way out of Europe. Be careful what you wish for would appear to be the message here.
Ronaldo wanted Real Madrid for two years before he left and it would be too soon to have regrets. The surprise is that, so far, Manchester United have not been given reason to rue his departure, either. Rooney has seen to that. He has confounded expectations with 30 goals and is on course to overtake Ronaldo's 42.
If he does it will be one of the greatest feats in the history of the modern game. Ronaldo scored 42 goals naturally. His total grew organically through the season, without pressure.
Rooney, by contrast, knew he had to make up Ronaldo's shortfall. It seemed, to these eyes and many others, an impossible, overwhelming task. He is on course to achieve it, and more. Madrid, meanwhile, will host the Champions League final this season, but will not feature in it. If Rooney and Ronaldo are to go head-to-head this season it will be at the World Cup, not the Bernabeu.
Losing Ronaldo has, strangely, given Manchester United a new player. On nights like this, Rooney would once have been consigned to the wide channels, with Ronaldo played down the centre. Sir Alex Ferguson could not trust Ronaldo to perform the first duty of the high, wide player, which is to stop the full back coming out. Rooney, he knew, was dutiful. Yet freed of these responsibilities and Rooney still expounds more energy, even in his new role Rooney has taken flight this season. He destroyed AC Milan here, the 7-2 scoreline a massive humiliation for the Italians.
Careful what you wish for: Ronaldo feels the pain of European defeat with Real Madrid
Quite simply, Rooney unnerved them. As promisingly as Milan started in the San Siro stadium two weeks ago, so United began here, and Rooney looked a monster of a player. In many ways, watching him now underlines how exceptional Barcelona were last season because to have this player, and Ronaldo with seven goals still the top scorer in the Champions League, despite Madrid's exit in the same team and not to win the competition seems barely believable.
The only explanation can be that when Ronaldo was here, Rooney was unable to influence the game in the same way and was often relegated to the role of high-class water carrier. He is too good for that, but it says something of the man that he never complained.
Maybe that is Manchester United's secret this season: 11 water carriers, where previously there were 10. Ronaldo knows his worth to any team does not lie in defence but Rooney has never been too proud to put in a shift. He scores headers like an old-fashioned centre half and does the donkey work like one, too.
When Gary Neville provided the cross for his first goal and then jumped into his arms, it was the coming together of a shared philosophy that has stretched across generations under Sir Alex Ferguson at Old Trafford. Age, and some would argue plenty of ability, may separate them, but they share a work ethic that comes straight from the top.
Top dog: Rooney outjumps Milan defender Daniele Bonera to put United in front
United's ethos shone through here. Madrid are not a team this season, they are a project, the vision of Florentino Perez, the owner, who assembled one group of galacticos in his first term and has now put together another. The old problems remain, though: a team built around the talent of two or three outstanding forwards is as lop-sided as one that is focused solely on defence and counter-attack.
United are far from the finished article, particularly at the back, but they have greater balance and last night it showed. Milan had the odd moments, but the return of Rio Ferdinand and Nemanja Vidic makes a huge difference, and Rooney is irresistible.
The best in the world right now? Probably.
We hear much about Milan Lab, the scientific centre based at the Milanello training complex where age does not matter and fitness is all. Yet, Rooney aside, the most impressive aspect of last night's win was the contribution of players such as Gary Neville and Paul Scholes.
There are few tributes to the expert knowledge and laboratory analysis behind their longevity, but it would appear something more important is at work. It cannot be bottled, taken with water, or printed out, run through a computer and broken down to six decimal places. It does not need to be picked over by a team of white-coated technicians, because it cannot be seen, even under a microscope. It is what has separated Manchester United from the pack for many years now.
Milan Lab can pile up data until the floorboards creak under the weight of information; none of it matters if Ronaldinho, a genius, lacks the application at 29 that Neville,a pack horse, has at 35. Analyse that, as the saying goes.
Manchester United 4 AC Milan 0 (agg 7-2): Wayne Rooney's nod to greatness as Rossoneri flattenedManchester United 4 AC Milan 0: The action as it happenedMANCHESTER UNITED FC