Arjen Robben's seventh league goal of the season and Petr Cech's penalty save sealed a gritty 1-0 victory for league leaders Chelsea at Blackburn Rovers on Wednesday.
The Londoners, far from their fluent best in a prickly encounter at Ewood Park, scrapped to an eighth consecutive league victory to move 11 points clear of Manchester United.
With 13 games remaining, Chelsea have 64 points, United 53 and Arsenal, who lost 4-2 at home to United on Tuesday, are a distant third on 51.
Elsewhere, fourth-placed Everton maintained their quest for Champions League football with a 1-0 victory over Norwich City, Birmingham City beat Southampton 2-1 and Manchester City drew 1-1 with Newcastle United.
Aston Villa's Colombian striker Juan Pablo Angel scored one goal and missed two penalties as his side drew 1-1 at Fulham.
After the fireworks at Highbury 24 hours earlier, Chelsea relied on old fashioned hard graft to overcome Blackburn, who provided an intimidating physical test.
Cech, who beat former Manchester United goalkeeper Peter Schmeichel's English Premier League record of 694 minutes without conceding a goal, proved the hero after Robben had given them the lead after five minutes.
The Dutch winger raced on to Frank Lampard's long pass and drove a shot through keeper Brad Friedel from a tight angle before limping off following a heavy tackle by Aaron Mokoena.
Rovers were awarded a penalty after 34 minutes when Paulo Ferreira brought down Robbie Savage, but Cech dived low to his left to keep out Paul Dickov's firm spot-kick.
The last goal the Czech international conceded was in the 2-2 draw at Arsenal in December.
Chelsea rarely threatened to extend their lead in a bad-tempered second half that degenerated into a running battle between the hot-headed Dickov and Chelsea skipper John Terry.
Ugly scuffles littered the closing stages as Chelsea dug deep to preserve their lead and their players greeted the final whistle with wild celebrations as their first title in 50 years edged closer.
"There are still a million miles to go," Terry told Sky Sports. "We've shown we can play football at home, but we've come away and battled and fought.
"Manchester United will fight us all the way to the death but if we keep winning they'll die off."
FURTHER PROOF
Manager Jose Mourinho said the victory was further proof that his players will not crumble.
"It wasn't a good game of football it was a fight," said the Portuguese. "May be they thought we were a group of kids coming from London and not ready for this, but we are ready.
"Blackburn had a special attitude, but our spirit was amazing. We need nine victories and one draw to be champions."
Gary Doherty's late own goal condemned Norwich to an unlucky defeat at Everton, who are now just four points behind champions Arsenal.
Alan Shearer blasted his 250th Premier League goal to give Newcastle United an early lead at Manchester City, for whom another former England striker, Robbie Fowler, equalised from the penalty spot.
It was a tale of missed penalties at Craven Cottage, with Angel the chief culprit as Villa were denied a rare away victory by Lee Clark's stoppage-time equaliser.
Angel headed Villa in front, Andy Cole then missed from the spot for Fulham before Edwin van der Sar twice denied Angel his 50th goal for Villa.
Southampton stayed four points adrift of safety after losing 2-1 at Birmingham City for whom Uruguayan striker Walter Pandiani, signed on a loan from Deportivo Coruna, marked his debut with an early goal.
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