Why are we asking this now?
Manchester United had never beaten AC Milan, the seven-times European champions, on their own ground, the San Siro, until Tuesday night when Rooney, now 24, carved apart one of the great defences in world football to score twice in a 3-2 win. In the past month he has scored four times against Hull, struck the winner against Manchester City in the Carling Cup semi-final and swept Arsenal aside on their own pitch. He is the one Englishman who would qualify automatically for a World XI in any interplanetary Champions League.
What makes him special?
He treats even internationals with the same unfettered lack of inhibition as he did when kicking a ball around the playground of the De La Salle school in Croxteth, where he grew up, in the deprived, decaying heart of Liverpool. You will find him everywhere on the pitch; on the wings, in central midfield and even tackling back in his own defence. When training with Manchester United, he often likes to go in goal. Before kick-off you will find him in the dressing room, juggling a ball with his feet – a game he used to share with Cristiano Ronaldo.
How do Ronaldo and Lionel Messi compare?
Ronaldo and Messi look like athletes; the former is tall and graceful, while the Barcelona striker is small and lithe. Rooney looks like Shrek. But when it comes to conjuring marvellous things from a football, he is at least their equal. He is more of a team player than Ronaldo, who despite the spat that saw Rooney dismissed in the last World Cup, he likes. In international football, Rooney has played better for England than Messi has done for Argentina. At the age of 18, he performed superbly in Euro 2004.
Is he a 21st-century Paul Gascoigne?
Superficially, yes. Both grew up on deprived northern council estates with a God-given talent for football and not much else. Both escaped their boyhood clubs, Newcastle and Everton, for something bigger. But Sir Alex Ferguson always wondered what would have happened had he signed Gascoigne as he nearly did in 1988. Ferguson has controlled Rooney, limiting his commercial endorsements to four and exercising his iron discipline off the pitch. Rooney has fewer mental demons than Gascoigne and his vice is sweets rather than alcohol.
Why is he at Manchester United?
One similarity with Gascoigne is that they both found their home city something of a village and felt claustrophobic. Rooney lived for Everton, his bedroom was a shrine to the club and he was a child mascot at Goodison Park. But his relationship with his manager, David Moyes, was abrasive, finishing up in the libel courts, where Moyes won a six-figure sum after Rooney accused him of leaking stories about him to the Liverpool Echo. By then he had been transferred to United for what now seems like a bargain fee of about £24m.
How crucial is he to Fabio Cappello?
Put it this way; England's slumps in form have coincided with injuries to Rooney. But for breaking a bone in his foot in the first half, England may well have beaten Portugal in the Euro 2004 quarter-final. In 2006, barely six weeks before England left for a World Cup they were expected to dominate, Rooney broke his foot again – and with him half-fit they stank the tournament out. When Ronaldo winked at his manager, Phil Scolari, after he goaded Rooney into a red card in the quarter-final in Gelsenkirchen, it was a way of saying, "Job done".
What explains his form?
Ronaldo's departure for Real Madrid has meant that Rooney is the undisputed main man at Old Trafford, in a way he always looked like being when announcing his United debut with a hat-trick against Fenerbahce in the Champions League six years ago. Rooney has thrived on the responsibility while at the same time Ferguson has given him a more defined role as a central striker that has led to his best ever season in terms of goals. Great strikers tend to be selfish footballers and selfishness is a quality Rooney has been slow to learn.
Where does he fit in the England set-up?
Rio Ferdinand was the immediate beneficiary of John Terry's disgrace but Rooney looks the likeliest long-term bet to be captain. In part it is to do with age. The so-called Golden Generation – Beckham, Gerrard, Lampard, Ferdinand and Joe Cole – are all in their late twenties or early thirties. They're unlikely to be around for the World Cup in 2014. Rooney is 24 and, as the national side breaks up post-South Africa, Capello or whoever succeeds him may give Rooney the armband on the grounds that he is the best player, just as Glenn Hoddle turned to Alan Shearer in 1996.
Any off-field skeletons in the cupboard?
There were some unfortunate stories about liaisons with prostitutes, one of whom turned out to be a grandmother, but he was a teenager on Merseyside then and his relationship with Coleen and fatherhood has made him more mature and perhaps a bit boring. He does tend to enjoy staying in and spending quality time with his Playstation and watching The Sopranos. Coleen, the one-time head-girl at De La Salle, has rather more up top than the average WAG. Their best friends are Steven and Alex Gerrard, who have also managed to keep their private lives largely confined to the odd spread in OK! magazine.
Will he go abroad soon?
The critical thing about his club's debt is that at £700m it is so huge that selling a player even for a Ronaldo-sized fee of £80m wouldn't make much of dent in it. Gascoigne went to Lazio in 1992 and David Beckham left Old Trafford for Real Madrid. But in Gascoigne's time, abroad meant more money – which is not the case now – and Beckham's relationship with Ferguson had collapsed. One thing everyone who knows Rooney can agree on is that they cannot see him poring over a Spanish or Italian grammar book. He might be tempted back to Everton towards the end of his career.
What about when the football's all over?
Aside from probably becoming quite fat and bald, nobody really knows what will become of him. Great footballers, in Britain at least, rarely make good managers. Gascoigne lasted 39 days at Kettering Town while Sir Bobby Charlton was a disaster at Preston. And although Rooney is not quite so inarticulate as he once was, Alan Hansen's space on the Match of the Day sofa does not appear under immediate threat. Still, the finish line is a decade away and by then young Kai Rooney will probably be tearing round the football pitches of England like his dad.
Do England's World Cup hopes depend on Rooney?
* A winning team needs to pick up momentum through the tournament. Rooney is likeliest to provide it
* Opposition coaches will adapt their games when facing him – which is what Capello wants
* Rooney has the class to cut through even the best international defences
* Football is not an individual sport. As Germany continually prove, the best teams usually make the final
* Unless England fall dramatically behind, genius is a quality they might not need to call upon
* Capello is quite simply too good a manager to base his campaign on the performance of a single footballer