LONDON: A Wayne Rooney hat-trick fired Manchester United back to within two points of Chelsea at the top of the Premier League as the champions inflicted a 4-1 defeat on Portsmouth in Avram Grant's first match in charge.

The England striker converted two penalties either side of a first-time finish from a Ryan Giggs pass to help United to a win that increases the pressure on Chelsea to take something from Sunday's trip to Arsenal.

Giggs completed a good afternoon's work for Sir Alex Ferguson's side by claiming the 100th Premier League goal of his career with a late free-kick.

Portsmouth had appeared galvanised by the new manager but their good early work was undone when Michael Brown pulled down Rooney to concede the opening penalty.

Kevin-Prince Boateng equalised with another penalty after Tomasz Kuszczak was adjudged to have fouled Frederic Piquionne.

But Rooney re-established United's lead three minutes after the restart and then killed the contest by sending Asmir Begovic the wrong way after Piquionne had brought down Giggs.

The defeat leaves Portsmouth three points adrift at the bottom of the table with just seven points from 14 matches, underlining the scale of the task former Chelsea and Israel manager Grant has taken on.

Manchester City's run of draws was extended to seven matches after Mark Hughes's side were held to a 1-1 stalemate at home to Hull.

Shaun Wright-Phillips gave City the lead in first-half stoppage time with a 25-yard shot that found the net with the help of a deflection off Hull defender Anthony Gardner.

But City paid the price for failing to convert a string of second-half chances when Joleon Lescott was adjudged to have handled in the area with eight minutes left.

Jimmy Bullard converted the penalty to extend Hull's unbeaten run to four matches.

West Ham were the day's highest scorers with Gianfranco Zola's men claiming a badly-needed boost to morale by beating Burnley 5-3 at Upton Park.

Jack Collison, Junior Stanislas and Carlton Cole, from the spot, ensured the Hammers were in the driving seat by half-time.

Guillermo Franco and Luis Jimenez extended the lead before a Steven Fletcher double and a Chris Eagles strike made the score more respectable for the visitors, who finished with ten men after Steven Caldwell was ordered off for a professional foul.

Wigan bounced back from last weekend's 9-1 mauling at Tottenham with a battling display to earn a 1-0 win over Sunderland that was sealed by Colombian striker Hugo Rodallego's 76th-minute strike.

Damien Duff rescued a point for Fulham with a 75th-minute equaliser against relegation-threatened Bolton at Craven Cottage.

Ivan Klasnic had given the visitors hope of a badly-needed victory by firing them into the lead ten minutes before the interval.

Saturday's other 1500 GMT kick-off, between Blackburn and Stoke City, ended goalless.