Manchester Utd 2 Portsmouth 1: Rooney sorcery is one for old guard

England striker's genius mesmerises David James as United make a mockery of Dad's Army jibes with FA Cup win

No one has established whether the plane flying over Manchester United's Carrington training ground last week was on a spying mission, but if it was, you can guarantee it was not uncovering information about Wayne Rooney. What more could be learned?

Only to predict the unpredictable, perhaps, which would sum up his performance in this FA Cup fourth-round tie last night. Coming on with half an hour to go, Rooney transformed a difficult contest against Portsmouth with two goals. The first was simple, the second outstanding.

Receiving the ball 30 yards out, he accelerated, drew his foot back as if he was planning to unleash thunder, and then chipped exquisitely over David James into the top corner. It was a goal worthy of winning the Cup itself and Sir Alex Ferguson will have drawn satisfaction that it was scored with only seven minutes to go. That, Arsène Wenger is alleged to believe, is deep into the time when United are supposed to wilt.

In fact, both Rooney's goals came after the 70-minute mark but to be fair to the Arsenal manager, Portsmouth did score in the closing moments, Pedro Mendes' shot deflecting off Kanu and past Tomasz Kuszczak's dive. Nevertheless, Ferguson could not resist commenting: "I thought Portsmouth were beginning to look tired when we scored." Touché, Mr Wenger.

On Rooney's second goal, he added: "It was a marvellous piece of imagination and audacity. He had a freshness about him. He lit the place up as soon as he came on. If he gets a run of goals, it'll make a big difference to this team." The big difference yesterday was in the age of Ferguson's side. Perhaps stung by Wenger's theory, he went to the opposite extreme, leaving Rooney on the bench and resting fellow youngster Cristiano Ronaldo completely. Ole Gunnar Solskjaer and Henrik Larsson formed a strike force with a combined age of 68. And, in case that duo flagged, the rest of the team was sprinkled with 30-somethings, namely Ryan Giggs, Paul Scholes and Gary Neville.

In keeping with the theme, Portsmouth included a United old boy, too, and Andy Cole formed enough of a distraction after four minutes to allow Gary O'Neil to steal in behind the home centre-backs, a threat that was only dispelled by Tomasz Kuszczak's diving at the Pompey captain's feet. O'Neil claimed a penalty; the television evidence was not conclusive.

Nor was it damning nine minutes later when Nemanja Vidic believed he had opened the scoring with a powerful header from Ryan Giggs' corner. David James took some of the pace off the ball but it needed Pedro Mendes to clear just before the full circumference had crossed the line.

United upped the tempo and were unfortunate not to score before the interval. Glen Johnson almost ran Giggs' pass into his own net after 38 minutes and his blushes were saved only by James kicking the ball away as he lay on the ground. A minute later the Portsmouth goalkeeper made a more conventional stop, reaching to tip Michael Carrick's header over the bar.

Neville forced James to dive low to his left after the break but Cole probably should have put Pompey ahead after 54 minutes when Mendes pulled back from the right. Instead of trusting his left foot, Cole prodded with his right and the shot lacked power.

Larsson lashed a ferocious volley past James two minutes later only to have his effort disallowed incorrectly for offside, and Scholes forced a flying save from the Portsmouth goalkeeper. But Old Trafford was getting impatient and the cries for Rooney were getting louder before Ferguson introduced him.

The effect was instantaneous, but even Rooney's exertions seemed likely to prove futile when United took the lead after 77 minutes. Larsson played a clever ball to the left that pushed Giggs beyond the retreating rearguard and when he crossed low to the edge of the six-yard box, Rooney side-footed in.

That was straightforward finishing, the second was extraordinary. At the end a cold Manchester night echoed loudly to "Rooney, Rooney". So loud you could have heard it in a plane.