London: Cristiano Ronaldo scored twice for the second successive match as Manchester United extended their lead at the top of the English Premiership to four points with a 3-1 win against Wigan at Old Trafford on Tuesday.

United's title rivals Chelsea lost ground after the reigning champions, still second, could only manage a 2-2 draw at home to Reading.

Liverpool, who began Boxing Day in third place, dropped to sixth after a 1-0 defeat away to Blackburn where South Africa striker Benni McCarthy scored the only goal.

Arsenal went third with a 2-1 win away to bottom-of-the-table Watford in the late kick-off match.

Bolton climbed a place to fourth after a 2-1 win at home to Newcastle while Portsmouth, up into fifth, kept their European hopes alive with a 2-1 victory away to West Ham.

Tottenham ensured Aston Villa's barren spell continued with a 2-1 home success.

Stephen Ireland's first goal for Manchester City secured a 1-0 win at fellow strugglers Sheffield United while Everton and Middlesbrough played out a goalless draw.

Despite the win, United manager Sir Alex Ferguson refused to get carried away.

"There will be some difficult days ahead. But after the West Ham result (where United lost 1-0 earlier this month) we've shown we can bounce back.

"Both of us (United and Chelsea) will drop points."

Ronaldo, who scored twice in United's 3-0 win over Villa on Saturday, was on the scoresheet barely a minute after coming on as a substitute at the start of the second-half for Darren Fletcher.

He headed in a Paul Scholes corner and four minutes later the Portugal international made it 2-0 after South Korea's Park Ji-Sung was brought down in the box by Gary Teale for a penalty.

Ronaldo's spot-kick was parried by Wigan keeper Chris Kirkland but the winger scored from the rebound.

Ole Gunnar Solskjaer added a third goal on the hour mark before Wigan's Leighton Baines scored from a penalty in the closing seconds.

Two goals from in-form striker Didier Drogba looked to have wrapped up three points for Chelsea but Reading twice drew level at Stamford Bridge.

"That was a fair result," said Chelsea coach Jose Mourinho.

"When the opponents do well and create problems, you can't complain, only praise the opposition," he said.

Ivory Coast international Drogba put Chelsea ahead with a header from a Frank Lampard corner seven minutes before half-time.

But Leroy Lita levelled in the 67th minute with a diving header from close range after a cross from Glen Little.

However, barely five minutes later, Drogba restored Chelsea's lead when he headed in a curling centre from Shaun Wright-Phillips.

In the 85th minute Reading were level thanks to a bizarre own-goal when Chelsea and England full-back Ashley Cole's hurried clearance hit team-mate Michael Essien and went past keeper Hilario.

Liverpool manager Rafael Benitez was left disapppointed by his team's defeat at Ewood Park.

"We had a lot of clear chances but we didn't score. If you miss these opportunities and you make a mistake then you will be punished."

Rovers manager Mark Hughes praised McCarthy.

"Benni was great. While he's adjusting to the Premiership he's still scoring goals."

Portsmouth were indebted to two headed first-half goals from Linvoy Primus - the central defender's first goals since Boxing Day 2004 - for their win.

Although veteran Hammers striker Teddy Sheringham pulled a goal back nine minutes from time, Pompey had done enough.

"We went two-up and had control of the game," said Portsmouth manager Harry Redknapp. "I thought we deserved the win."

West Ham's defeat was their first under new manager Alan Curbishley after a win over Manchester United and a draw away to Fulham.

Newcastle went ahead in the eighth minute through Kieron Dyer at the Reebok Stadium but defender Peter Ramage's own-goal saw Bolton level before Nicolas Anelka completed the comeback just before the hour.

Arsenal captain Gilberto Silva scored his third goal in as many games in the 19th minute before Tommy Smith equalised four minutes later for Watford.

The bottom club were in sight of a point when Arsenal's Dutch international striker Robin van Persie scored his 11th goal of the season, seven minutes from full-time.

Tottenham's victory over Aston Villa meant Martin O'Neill's men had now gone eight games without a win.

England striker Jermain Defoe struck twice for Spurs in the second-half before Villa captain Gareth Barry netted in the 81st minute.

Second-bottom Charlton play their first match under new manager Alan Pardew against Fulham on Wednesday.