United currently have no such problems and were able to rest several key players as they brushed aside the challenge of Watford who remain stuck at the bottom and seven points adrift of safety.
A Cristiano Ronaldo penalty on 20 minutes, a Lloyd Doyley own goal and strikes from Henrik Larsson and Wayne Rooney gave United a comfortable win.
After a week's holiday in Dubai, Ronaldo was in irrestible form and continued his personal battle for the golden boot by bagging his 14th league goal of the season after Ole Gunnar Solksjaer was fouled by Jay DeMerit.
United, who rested Edwin Van der Sar, Ryan Giggs and Paul Scholes, increased the tempo after halftime and forced Doyley to head into his own goal on 61 minutes before Larsson scored his first Premier League goal and Ronaldo set up Rooney for a superb lob for the fourth.
"We've got a good squad of lads. There's a great spirit among them," Sir Alex Ferguson said before confirming there would be no late bid for Bayern Munich's England midfielder Owen Hargreaves.
|Rooney reacts to suggestions |
his lob was a fluke [AFP]
Chelsea, now on 54 points, did what they needed to with Didier Drogba notching his 15th league goal of the season on six minutes when he picked up Frank Lampard's weighted pass and drilled a left-foot shot into the bottom corner.
The impressive Andriy Shevchenko was twice denied but Blackburn also threatened and could easily have grabbed an equaliser against Chelsea's recently shaky defence.
Benni McCarthy missed a header for the visitors, who also had a penalty appeal turned down, while Ricardo Carvalho was forced to clear Matt Derbyshire's effort of the line.
Lampard killed off Blackburn's hopes though midway through the second half when he belted in a trademark 30 metre shot before Salomon Kalou scored late on.
More injury woe
It was not all good news though as Cole was stretchered off with what looked like a serious injury after jarring his knee.
He will almost certainly be out of England's friendly international against Spain in Manchester next week and could even be a doubt for their next Euro 2008 qualifier in Israel on March 24.
Cole landed awkwardly after stepping on the ball and looks likely to join fellow defenders Khalid Boulahrouz and captain John Terry on the sidelines for Chelsea.
"He's not ok...he can't walk. It must be something serious," Mourinho said.
| Pld Pts
1. Man United 25 60
2. Chelsea 25 54
3. Liverpool 25 49
4. Arsenal 24 45
5. Bolton 25 41
6. Portsmouth25 38
In other games on Wednesday, Newcastle United beat Aston Villa 3-1 despite Villa having the best of the game for long periods. Relegation-threatened Charlton Athletic drew 1-1 at Bolton Wanderers.
Elsewhere on Wednesday Newcastle’s James Milner showed Aston Villa what they were missing as he scored his side’s first in a 3-1 win at St James’ Park.
Milner spent last season on loan at Villa and was unhappy when a proposed permanent move to the club broke down at the last minute in August.
But he has since flourished on Tyneside and scored for the third game in succession to send Glenn Roeder's team on the way to their first home win in five matches.
Milner scored after just four minutes before setting up Kieran Dyer for Newcastle’s second after seven, in an explosive start.
But Villa fought back in a lively match and their new signing from Watford, Ashley Young reduced the arrears.
Young had several opportunities to level the match but in the end French substitute Antonine Sibierski scored Newcastle's third goal in stoppage time.
Meanwhile Charlton secured an unlikely point in their battle for Premiership survival after a 1-1 draw with Bolton at the Reebok Stadium.
The visitors were forced to survive a sustained onslaught for the home side, and also Charlton had reason to be grateful to Bolton's Jussi Jaaskelainen, who gifted them their equaliser.
|Charlton had to withstand fierce |
home pressure to claim a point [Reuters]
The Finnish goalkeeper failed to hold an innocuous long-range free-kick from Talal El Karkouri in the 12th minute and the ball spun into the net.
That came just four minutes after Bolton's Danish forward Henrik Pedersen had met Gary Speed's cross with a fine glancing header to get the home side off to the perfect start.
There might have been an element of good fortune about it, but Alan Pardew's side will welcome a result that moved them to within two points of Wigan, the club currently occupying the last survival spot in the division.
They are now level on points with west ham after the east London side lost 2-1 at home to Liverpool on Tuesday.