The England striker had gone 10 games without scoring but that run ended in the 10th minute at the Reebok Stadium when he shot past Jussi Jaaskelainen.

And six minutes later Rooney doubled United's lead over their third-placed opponents with a brilliant curling shot.

Cristiano Ronaldo shot into an empty net eight minutes from time before Rooney completed his treble in the closing stages.

"He was due to score at some point," United manager Sir Alex Ferguson said of Rooney.

"I was just pleased he got off the mark. The longer these things go for strikers, they start to doubt things. When they score their confidence goes up.

"You could see as soon as he (Rooney) scored, there was more to come," he also told Sky Sports.

Reigning champions Chelsea remained level on points with the leaders after a 2-0 win away to Sheffield United while Liverpool ended Aston Villa's unbeaten start to the season with a 3-1 victory at Anfield.

Elsewhere, Arsenal came from behind in a 1-1 draw with Everton and Portsmouth moved above the Gunners into fourth place by beating Reading 3-1 at Fratton Park.

Watford, the only team yet to win in the Premiership this season, were held to a goalless draw at home to Tottenham as Wigan's 1-0 win against Fulham gave the Latics their first away victory since March.

Charlton remained bottom of the table after being held to a goalless draw away to Newcastle in Saturday's late kick-off.

Second-bottom West Ham are at home to Blackburn on Sunday while struggling Manchester City play Middlesbrough in Monday's match.

At Bramall Lane, Chelsea's third-choice keeper Hilario saved Danny Webber's poorly-struck penalty when the game was still scoreless after Didier Drogba was ruled to have fouled Claude Davis.

Chelsea then made the Blades pay when Frank Lampard's 30-yard free-kick deceived Paddy Kenny two minutes before half-time.

Early in the second-half England international Lampard's cross was headed in by German midfield colleague Michael Ballack.

But that didn't stop Mourinho complaining about the Blades' penalty.

"The decision for me was completely wrong," he told Sky Sports.

Frustrated Blades' boss Neil Warnock said: "Goals change games and it really would have been nice for once to put a penalty away and put a bit of pressure on them, take the lead and see how they reacted."

Villa, a transformed team this season under new manager Martin O'Neill, were brought back down to earth on Merseyside.

Liverpool boss Rafael Benitez found himself under pressure after defeat by Manchester United last weekend appeared to end his club's title hopes.

But that didn't stop the Spaniard changing his starting line-up for the 99th consecutive match.

Benitez's men went ahead in the 31st minute through Dirk Kuyt's volley and seven minutes later former Villa striker Peter Crouch made it 2-0 when the England international turned in Steve Finnan's cross.

And there was still time for Liverpool to score another before half-time when Crouch set up Luis Garcia.

Gabriel Agbonlahor pulled one back for Villa in the 56th minute.

"We had 42,000 supporting us in the Carling (League) Cup and we wanted to win for them today," said Benitez.

Arsenal started Saturday five points behind the leaders but with a game in hand.

However, they went behind in the 11th minute when Australia' Tim Cahill got on the end of Mikel Arteta's cross.

But Robin van Persie's 71st minute equaliser gave the Londoners a share of the points.

"The way the players performed was excellent," said Everton manager David Moyes. "We had to withstand an awful lot of Arsenal pressure."

Portsmouth went ahead when Pedro Mendes's 10th minute corner was headed into his own net by Reading's Brynjar Gunnarsson.

Nwankwo Kanu headed in his seventh goal of the season early in the second-half before Mendes's 66th minute volley sealed victory. Kevin Doyle grabbed a late consolation goal.

Watford, on the stroke of half-time, saw Ashley Young net against Spurs but the winger's effort was controversially disallowed for offside.

"Looking at the monitor, it was a goal. Sometimes these things go for you, sometimes not," said Watford manager Aidy Boothroyd. "But it was another clean sheet and we are becoming hard to beat."

Henri Camara spared Wigan's blushes at Craven Cottage with an 83rd minute goal after Denny Landzaat's second-half penalty clipped the crossbar.