It is not matches against the likes of Manchester United that will decide Portsmouth's fate, but this was nevertheless Pompey's worst defeat, and United's biggest win, since August.
Add the knowledge that United are vulnerable at Fratton Park – they had lost three of six visits since Portsmouth returned to the top flight – and it is clear Avram Grant made a disappointing start in the Portsmouth dug-out.
Whether Pompey would have fared better under Paul Hart is irrelevant now, though the failings which undermined Hart – poor finishing and sloppy defending – were more evident than ever. "If we concentrate more in front of goal, and don't give away easy soft goals, we can [stay up]," said Grant.
Easier said than done. Portsmouth's poor concentration, at both ends, was underlined at United's opening corners. From the first Paul Scholes was left unmarked at the edge of the box, enabling Ryan Giggs to pick him out for a shot; a move the pair have only been doing for 15 years. The next was laid back by Antonio Valencia to Gary Neville. One defender went to close down Neville, but no one went to Valencia, enabling the Ecuardorian to receive the ball back and advance unchallenged into the box.
This is basic defending. Add in daft penalties conceded by Michael Brown and Frederic Piquionne, and Portsmouth, for all their neat passing, were skewered. Rooney converted both as part of his third United hat-trick but the conductor was Giggs, 36 yesterday. Peerless in possession he also curled in a free-kick for United's fourth, his 100th Premier League goal. Jamie O'Hara, no slouch with the left foot himself, said: "To play against Giggs is an honour. To be that good at 36 is incredible. Every time he gets the ball you're wondering what he's going to do because he can do anything with it."
"I don't know how he does it, he is unbelievable," added Rooney. Sir Alex Ferguson, having calmed down after Portsmouth received a soft penalty on the linesman's say-so, said of Giggs: "He's an exceptional player. A rarity. He will play for two years yet."
Who knows what division Portsmouth will be in then? When Grant said he had met Ali Al-Faraj, "one time or two I think", but not since becoming manager, one wondered again about the commitment of the club's absentee owner, and what presaged for the club.
Grant added: "I conduct discussions with [chief executive] Peter Storrie. I will know in the next couple of days what we can do in January."
The first target should be to extend O'Hara's loan to the end of the season. The Tottenham midfielder was, with Kevin-Prince Boateng, Portsmouth's best player and he now views the league table through his adopted club's eyes. "It is depressing when you go home and the results have gone against you," he said. "I feel for this club and we're seven points adrift. That's going to be a real battle to get out."
It is, and we should now find out whether Grant is good enough to deserve the jobs he keeps falling in to. His record at Chelsea was excellent, but is widely regarded as reflecting the quality of the playing and coaching staff he inherited from Jose Mourinho, rather than the result of his leadership. This time he inherits a spirited squad with potential, but which is a long way from safety and is under uncertain ownership. It is time for the Manager in Black to show there is more to him than Johnny Cash's dress sense and an impressive contacts book.
Portsmouth (4-1-4-1): Begovic; Ben-Haim, Kaboul, Wilson, Hreidarsson; Brown; Piquionne (Kanu, 62), Yebda (Utaka, 78), O'Hara, Boateng; Dindane (Smith, 81). Substitutes not used: Ashdown (gk), Vanden Borre, Hughes, Belhadj.
Manchester United (4-3-3): Kuszczak; Neville, Brown, Vidic, Evra; Fletcher, Scholes, Carrick (Anderson, 76); Valencia, Rooney, Giggs. Substitutes not used: Foster (gk), Owen, Berbatov, Park, Nani, De Laet.
Referee: M Dean (Wirral)
Booked: Portsmouth: Dindane, Boateng, O'Hara, Utaka Manchester United: Vidic, Neville, Scholes
Man of the match: Giggs