If Portsmouth keep playing like this, the Football Association may as well give them the FA Cup now. This is supposed to be the year of the underdog in the oldest cup competition in the world, but there is nothing small-time about Harry Redknapp’s team or their ambitions. On the day that West Bromwich Albion, their semi-final opponents at Wembley next month, lost 4-1 at home to lowly Leicester City, Portsmouth cruised past Aston Villa with the style and speed of a Rolls-Royce overtaking a Mondeo.

Proving that he is more than a wheeler-dealer, Redknapp has turned Portsmouth into a team who can beat anyone – they have won more away games than Arsenal and Liverpool this season, and have lost only twice at home. With a rock-solid spine of David James, Sylvain Distin, Sulley Muntari and Jermain Defoe, Portsmouth strolled into a 2-0 first-half lead against opponents who woke up and smelt the coffee only at the interval. “We’ve got good players,” Redknapp said. “The fans must be wondering what they are seeing.”

Portsmouth deserved the three points, but they were given a helping hand by Scott Carson, who had an afternoon that he will remember for all the wrong reasons. The England goalkeeper rushed off his line twice and was punished both times, first by Defoe’s exquisite chip, then by a comical own goal by Nigel Reo-Coker.

To make matters worse, Fabio Capello, the England manager, was at Fratton Park to witness a display that will probably cost Carson his place in the England squad for the friendly against France a week on Wednesday. If that was not enough, James, the 37-year-old England No 1, caught the eye in the Portsmouth goal, with stunning saves from John Carew and Ashley Young.

“David James is an exceptional talent and has matured into his job,” Martin O’Neill, the Villa manager, said. “The possibility of making mistakes does not faze him and I hope that’s also the case with Scott. I’ve got Scott on loan for a year from Liverpool and, so far, I’ve been very pleased with him.”

O’Neill wants to sign Carson in the summer and Liverpool value the goalkeeper at £10 million, but, after this display, the Villa manager may be tempted to get back to Rafael BenÍtez and knock a zero off the price. Carson’s first rush of blood to the head came after 11 minutes, when he sprinted off his line and allowed Defoe to score for the sixth time in six matches. He was at it again seven minutes before half-time when his attempted clearance struck Reo-Coker, 30 yards from goal, and rebounded into the net.

Villa regrouped after the interval and were dangerous from set-pieces, but Gabriel Agbonlahor, Young and Marlon Harewood, a substitute, could not find a way past James, even after Portsmouth were reduced to ten men when Muntari was sent off for a second booking after pulling Moustapha Salifou’s shirt in the 79th minute. Ten minutes later, Chris Foy, the referee, showed Olof Mellberg a second yellow for the same offence, on Lassana Diarra. “They were nothing,” Redknapp said. “I thought the referee would let them go.”

Muntari’s sending-off was harsh, but it was not the main talking point among Portsmouth supporters as they filed out of Fratton Park after the PA announcer had relayed news of their local rivals’ latest embarrassing result. “Hull City 5 Southampton 0.” Life does not get much better than this if you support Portsmouth.

How they rated

Portsmouth (4-4-2): D James 8 – G Johnson 7 H Hreidarsson 7 S Distin 8 Lauren Y 6 – P Bouba Diop Y 7 L Diarra 8 S Muntari Y R 7 N Kranjcar 6 – M Baros 7 J Defoe 8
Substitutes: J Utaka (for Defoe, 81min), Kanu (for Baros , 83).
Not used: J Ashdown, L Aubey, P Mendes.
Next: Tottenham (a).

Aston Villa (4-4-2): S Carson 4 – O Mellberg Y R 5 Z Knight 5 M Laursen 6 W Bouma 6 – A Young 6 G Barry 6 N Reo-Coker 6 S Maloney 5 – G Agbonlahor 5 J Carew 6
Substitutes: M Harewood 6 (for Maloney, 57min), M Salifou (for Bouma, 79).
Not used: S Taylor, S Petrov, I Osbourne.
Next: Sunderland (h).