Cristiano Ronaldo again proved the difference as Manchester United hung on for a 3-2 home win over 10-man Reading.
The Portuguese winger struck twice in the second half to send United six points clear heading into 2007 after Chelsea's 2-2 home draw with Fulham.
Ole Gunnar Solskjaer headed United into the lead before poor goalkeeping from Edwin van der Sar allowed Ibrahima Sonko to nod Reading level.
Either side of Ronaldo's double, substitute Sam Sodje was sent off for Reading before Leroy Lita set up a tense climax with a cool finish in the last minute.
Reading stuck with the XI which held Chelsea to a draw on Boxing Day, with lone striker Lita giving Mikael Silvestre some uncomfortable moments in the first half.
The in-form Ronaldo had the first chance of the game when sent clear by Wes Brown, but selfishly shot straight at Marcus Hahnemann from an angle.
Lita turned Silvestre with ease before slashing a shot wide, while Glen Little scuffed an effort off target after penetrative work by Kevin Doyle down the left.
United controlled possession, but Reading decamped to the central portions of the field to restrict the Premiership leaders' sights at goal.
Wayne Rooney could not get a clean contact on one volley and also headed meekly at Hahnemann from Rio Ferdinand's ball into the box.
In between, Hahnemann spilled Ronaldo's header from a corner and Reading skipper Graeme Murty, along with his keeper, reacted quickly to block Solskjaer's shot on the rebound.
Solskjaer was not to be denied on 33 minutes as he took advantage of slack defending from Sonko to dart across the line and head Ronaldo's inviting cross beyond Hahnemann.
Sonko was quick to make up for his dozy defending by heading Reading level five minutes later. Nicky Shorey curled in a dangerous, deep free-kick and the Senegal centre-half glanced it past Van der Sar, who arrived too late with his punch.
United could easily have been back in front inside a minute as Ronaldo headed a Michael Carrick corner against the crossbar.
Ryan Giggs came on for Park Ji-sung at half-time and United started to enjoy even greater dominance of the game, with Hahnemann saving Solskjaer's header at point-blank range.
Rooney then shot over the bar after slipping on impact with the ball and minutes later curled another attempt over the bar after being released by Ronaldo.
The Portuguese winger was once more the stand-out performer for United and another teasing cross was flicked into the side-netting by Giggs.
Just before the hour and United reclaimed the lead after a slick passing move involving Giggs and Rooney found Solskjaer on the corner of the box.
The Norwegian nudged the ball past Sonko before seeing his precise shot come back off the post to Ronaldo, who scuffed home the rebound.
Reading were then given a mountain to climb when Sodje, having only been introduced as a substitute 10 minutes earlier, picked up a second yellow card on 69 minutes for tugging back Rooney.
Despite being reduced to 10 men, the visitors did have a chance to equalise when Steve Sidwell burst into the box to meet Shorey's cross, but his near-post header was off target.
For the third game in a row, Ronaldo finished the game with a brace as he side-footed home United's third on 77 minutes after being found unmarked at the back post by Giggs' cross.
Ronaldo was swiftly replaced, along with Rooney, but the threat did not subside as Hahnemann produced a smart save from Carrick's well-struck effort, and Darren Fletcher and Giggs both had chances to put the game to bed.
But Reading grasped a lifeline in the final minute as Lita capitalised on poor defending from Silvestre to slip the ball through Van der Sar's legs, and though they piled on the pressure to the final whistle, were unable to muster a dramatic equaliser.
