Manchester United legend Sir Bobby Charlton says he is surprised by the new-look team's 100% start to the Premier League season.
The Red Devils are top - two points clear of arch-rivals Manchester City - after five straight wins, having scored 21 goals and conceded only four.
They swept aside title rivals Chelsea 3-1 at Old Trafford on Sunday.
"You never know at the start what's going to happen but United have got off to a flier," Charlton, 73, said.
Manager Sir Alex Ferguson has dramatically lowered the age of the side with the regular inclusion of David de Gea, Phil Jones, Chris Smalling, Tom Cleverley and Danny Welbeck, while the likes of Ryan Giggs, Michael Carrick and Dimitar Berbatov have been left on the bench.
But United, who have often been slow starters in the past, have immediately hit top form in their opening fixtures as they aim for a record-breaking 20th top-flight title.
Charlton told BBC Sport: "It's a very unusual start for Manchester United but it's fantastic.
"The fans are enjoying it and even those who are just general football fans because of the way we play. Even the goals we are scoring are dramatic."
It is a remarkable turnaround for the 25-year-old, who had a huge fall-out with the club in October last year and publicly announced he wanted to leave.
He made his peace with his employers, signed a new five-year deal and is brimming with confidence.
Rooney has scored 156 goals for United from 329 appearances and is closing in on Ryan Giggs (160), Mark Hughes (163) and George Best (179) but he still has a long way to go before surpassing Charlton's all-time record of 249 goals.
Charlton, a World Cup winner with England in 1966, said of Rooney: "He is a marvellous player. You can tell he is very happy at the moment and he will score a lot more goals this season and beyond."
Ferguson is likely to give more young players an opportunity to impress when United face Leeds United in the Carling Cup on Tuesday.
Charlton was speaking on a visit to BBC Sport's new home at MediaCityUK in Salford to mark the launch of 2011 BBC Sports Personality of the Year.