Trebles in Saturday's 5-0 thrashing of Bolton Wanderers and the 8-2 hammering of Arsenal a fortnight ago have given the England forward a tally of eight league goals after four games and he has scored in every match.
It is a far cry from the wretched time he was enduring a year ago when off-field scandals, including the saga of whether he would stay at the club, and the loss of his scoring touch led to some critics questioning whether he was past his best.
"I had a long time to rest and I had a very good pre-season, I stayed clear of injuries and it's obviously helped me for the start of this season," he told ESPN television.
He has notched seven hat-tricks since joining United from Everton in 2004, the total number achieved by the great Bobby Charlton although still some way short of Denis Law's club record 18.
"It's a fantastic achievement considering he's only 25 and he's got many years in front of him," United manager Sir Alex Ferguson said.
Rooney's only hat-trick last season, which was completed in 14 minutes against West Ham United, was marred by a foul-mouthed tirade to a television camera that earned him a two-match ban.
This season there have been only smiles, shared by his team-mates who are revelling in Rooney's good form, the beginnings of which started towards the end of last season when his partnership with Javier Hernandez blossomed.
"We all know he is a world class player," said Hernandez.
