For Manchester United to be hunting another treble 11 months after the Carling Cup was the only trophy to make its way to Old Trafford is a lesson in self-renewal, and one Chelsea may care to study. The unprecedented trio of League, Champions League and FA Cup triumphs 12 years ago was so freakish that few in these parts expected to ever have a sniff of it again.
The miraculous one-off is encased in the club museum. But may it have a brother soon? After their 3-1 aggregate victory over a fading Chelsea side all the songs were of trips to Wembley, the stage for this year's Champions League finale (28 May) and Saturday's FA Cup semi-final against Manchester City.
This side may lack the glamour of the 1999 vintage or the star quality of 2008, when Cristiano Ronaldo and Carlos Tevez lined up alongside Wayne Rooney. But it could hardly be more committed, more sure of itself. Its strength was expressed by the relentless foraging of Park Ji-sung, the Zen wisdom of Ryan Giggs, the eagerness of Javier Hernández and the restored vigour of Rooney, who has been reborn in the withdrawn striker role behind Chicharito.
"He's enjoying the position he's playing in at the moment because he has a lot of freedom to use his energy," Sir Alex Ferguson said of Rooney. It was astounding that United were able to consign Chelsea to shadow without needing to summon Dimitar Berbatov, a forward of sublime skill. Chelsea went into battle with Fernando Torres, who cost £50m and was hooked at half-time. United struck the first blow with Hernández, a £6m buy who makes Torres look geriatric.
The 1999 tale was meant to be unrepeatable. It still has that feel, given that Barcelona look unbeatable in Europe. People always said it could not be done again. Competition would be too intense. The calendar would grow too demanding for any side to prosper on three fronts again. Now a double treble beckons.
Seven points clear of Arsenal in the Premier League, United face a City team who lost 3-0 at Liverpool on Monday night and will be without Tevez when a whole metropolis decamps to London to help the Football Association pay for their monument to hubris.
Clearly this is no time to be jumping to conclusions about City's prospects in that derby or even the threat still posed by Arsenal in the league. But for United to be in this position at all affirms their talent for reinvention. The 1999 campaign remains the zenith but 2007-08 ran it close. In that honeyed season United defended their league title before defeating Chelsea in a penalty shoot-out in Moscow.
In these spring days they have found a new strike combination to build a new age around. The leggy, high-stepping Hernández stretches the play with his sprints and Rooney links front and middle from the No10 position.
We are now on volume eight of the tactical study of Rooney's best role but maybe we can slam the book. With the fast-maturing Mexican to do most of his running England's No1 striker can see more of the attacking areas in front of him and make more creative use of space. He can veer left or right to work as an auxiliary winger.
The Rooney-Hernández duo is currently so vibrant that Berbatov can be left on the bench without it seeming wasteful. Chicharito's movement inflicted so much stress on Chelsea's defenders that John Terry decided an elbow was the only way to stop him. The England captain took him out with a jab of the arm in the 42nd minute, so Hernández responded by turning in an arcing Giggs ball 60 seconds later.
Chelsea had been forced by United's 1-0 away win at Stamford Bridge (and the £50m spent on Torres) to load the forward areas but there is no disguising the lethargy, the lack of conviction in Carlo Ancelotti's team.
As one good judge remarked the other day, Chelsea used to come over opponents in relentless blue waves. Not any more. An hour into this match, they were still groping for accuracy, for rhythm, as Ancelotti's reign approached the point of no return.
In a normal industry, scoring a League and FA Cup Double 11 months ago would keep you safe in your job, but this is football, this is Roman Abramovich, and all across this pitch there was evidence of Chelsea's staleness, their failure to renew and evolve. When a red card was shown for a foul on Nani it was one of the few fresh Chelsea talents who left the field: Ramires, the kind of bright young star Abramovich's lieutenants have been too slow to invest in.
This was a night of lunging tackles and desperate blocking by a side who just cannot cross the Rubicon of a first European title. Impeding their path, now, as in Moscow, are opponents who have mastered the skill of thinking two and three years ahead. Ferguson said: "I think we've hit form: the second half at West Ham, the performance at Chelsea, the performance here. It's a great boost." They all contribute at this restless, relentless club. Twelve years on, the treble is creeping out of its museum.