Manchester United 3 Portsmouth 0
Diego Forlan's third goal in as many appearances put United on their way before Cristiano Ronaldo - with his first Red Devils goal - and Roy Keane made the points safe in the final ten minutes.
With an experienced backbone to their team, Portsmouth were not overawed by their first Premiership visit to Old Trafford and enjoyed the early opportunities with Yakubu Aiyegbeni and Patrik Berger firing off target.
Nigerian striker Aiyegbeni's pace was posing problems to the United defence and his haranguing of Rio Ferdinand reaped an opportunity which was saved low at the near post by Tim Howard.
United were lacking invention, preferring to rely on grit rather than guile, with set pieces proving their best source of chances as Gary Neville's glancing header from a Ryan Giggs free kick was comfortably dealt with by Shaka Hislop and Forlan's corner was diverted away by Dejan Stefanovic.
The Premiership champions finally raised the tempo just before the half hour mark when Ruud van Nistelrooy brought the ball under control and unleashed a rasping volley which thundered off the top of the crossbar. The Dutchman then wasted a gilt-edged chance to break the deadlock by showing untypical profligacy to wildly blaze over after an incisive through ball from Giggs.
With the hosts gradually turning up the heat, the breakthrough came on 37 minutes as Forlan struck a measured volley into the bottom of the net after Neville's deep cross had been nodded back into his path.
The second half proved as equally scrappy as the first with Pompey always remaining a danger to their more illustrious hosts with Boris Zivkovic heading into the arms of Tim Howard.
A mistake from Darren Fletcher was almost capitalised on by the visitors but Patrik Berger's pass along the box just evaded United old boy Teddy Sheringham.
Despite United failing to seriously test Hislop, the home side should have doubled their advantage when Fletcher dinked the ball to the back post, with the Pompey keeper out of his goal. Nicky Butt's header from close range, though, was disappointingly wide of the upright.
With ten minutes remaining, The Red Devils wrapped up the win with substitute Ronaldo's vicious, low free kick helped on its way into the net by Hislop, who should have done better to keep the shot out.
To rub salt into the wounds, a second United substitute - captain Keane - made it three when he curled a delightful left footed shot into the corner of the goal but the end outcome was grossly unfair on the visitors.
