Manchester United continued to stalk the leaders by comfortably seeing off Southampton for a fourth successive Premiership win.
United laboured to break down a stubborn Southampton defence in a goalless first half.
But Paul Scholes ended the resistance by heading home from close range early in the second half.
Wayne Rooney then finished emphatically from Ryan Giggs' pass before Cristiano Ronaldo volleyed the third.
United pinned back Southampton from the first whistle, with Scholes having two early shots blocked and Rio Ferdinand heading wide from a corner.
It was 10 minutes before Southampton relieved the siege with Kevin Phillips winning a corner and there was an alarm for United as Graeme Le Saux's kick drifted across goal and Claus Lundekvam arrived too late to get a touch.
Ronaldo slipped the ball inside to Scholes after a pacy run, only for the former England midfielder to shin his shot.
For all United's pressure, Saints keeper Kasey Keller was first called into action on 18 minutes when he reacted sharply to snatch Alan Smith's cross ahead of Gabriel Heinze.
James Beattie's comeback from a calf injury lasted only 21 minutes before he limped off to be replaced by Dexter Blackstock.
Cristiano Ronaldo holds off Dexter Blackstock
Saints head coach Steve Wigley double-teamed Le Saux and Danny Higginbotham on Ronaldo and it worked as the Portuguese international was forced inside where he was often held up in heavy traffic.
United opened Southampton up for the first time on 34 minutes but Ryan Giggs played his cross in behind Rooney, who was unable to direct his header on target.
Giggs went closer himself, rasping a shot inches wide from 20 yards after Scholes rolled the ball into his path, and Keller was extended on 42 minutes when Ronaldo's snap shot almost surprised him at the foot of his left-hand post.
The on-loan Keller did even better on 44 minutes, diving full-length to beat away Rooney's full-blooded effort.
Southampton made a confident start to the second half when Telfer got forward to whip in a cross that Roy Carroll did well to clutch as Blackstock closed in.
At the other end, Rooney worked himself some space to whip a cross-shot across the face of goal which begged for a touch.
United's persistence paid off as they took the lead on 53 minutes with a scruffy - but important - goal.
Southampton failed to clear a corner and the bell fell to Ferdinand, who scuffed his shot across the face of goal but Scholes reacted quickly to nod home from close range.
It took United only five minutes to double their lead. Giggs weighted his pass perfectly to connect with Rooney's run and the youngster buried his shot from 12 yards.
Keller did his best to keep United at bay.
United were flowing now and Keller reacted brilliantly to tip away Ronaldo's free-kick as it came through a ruck of players.
Scholes then spotted Keller off his line and the American back-pedalled before arching up to tip the attempted lob over the bar.
As they tried to find a route back, Southampton pieced together a patient build-up, which ended with Higginbotham driving wide from 20 yards.
Ronaldo missed a golden chance, somehow spooning the ball over the open goal after Keller did well to parry Scholes' thumping shot.
But he made amends by volleying the third goal past Keller from eight yards out.
Man Utd: Carroll, Gary Neville, Ferdinand, Silvestre, Heinze,
Ronaldo, Keane, Scholes, Giggs, Rooney, Smith (Bellion 62). Subs not used: Howard, Brown, Miller, Fletcher.
Goals: Scholes 53, Rooney 58, Ronaldo 87.
Southampton: Keller, Nilsson, Jakobsson, Lundekvam, Le Saux,
Telfer, Delap (Fernandes 86), Anders Svensson, Higginbotham,
Beattie (Blackstock 22), Phillips. Subs not used: Blayney, Dodd, Crouch.
Ref: B Knight (Kent).