FA Premiership/Portsmouth 1 Manchester United 3: Mine deep down into football, through the stories of avarice and mendacity, of cheating and thuggery, and there are still diamonds to behold. One glistened here on Saturday when Ruud van Nistelrooy of Manchester United spoke in awe about the performance of Portsmouth's Lomana LuaLua, who had returned to the side following the death of his baby son.

"I have never seen anything like it," said the Dutchman. "What he did was show speed, technique and great strength in holding up the ball. He was a threat to us, to all our defenders, and kept going for 90 minutes.

"I just went over to him after the game and said, 'I wish you all the strength you need in this difficult time'. And I said to him, 'How you pulled off a performance like that I just don't know'."

Van Nistelrooy had been asked by the men from Sky to present the man-of-the-match bubbly to his team-mate Cristiano Ronaldo. But he said later: "There was only one man of the match for me and that was LuaLua. The way he played was unbelievable. I don't think he did anything wrong all game. In the circumstances it was an amazing display."

United's manager Alex Ferguson agreed. "I thought LuaLua was terrific for them, a real handful," he said. Sadly for Portsmouth, LuaLua's was an isolated excellence.

It is virtually impossible to imagine how Portsmouth may avoid relegation this season. When they are beaten in their next league game - for they will be at Chelsea - they will need 22 points from their remaining 11 games to reach the acknowledged safety mark of 40.

That is two points a game. In view of the fact that they have averaged only 0.65 of a point a game so far, the same as their goal ratio, it stretches credulity to breaking point to suggest that they can get there, especially as they have taken only one point from a possible 18.

And when they are relegated it is difficult to see them returning imminently, for their wreck of a stadium epitomises the whole club, which is without coherent structure. There is no academy to bring on young players and their chairman Milan Mandaric, with his bewildering turnover in managers, would appear to know as much about running a football club as his rival Rupert Lowe along the coast where there has been a similar revolving door. They will surely meet again next season, unless Southampton have dropped into League One by then.

The one thing Portsmouth do have, apart from a proud history, is their wonderful support - excluding the boneheads who cheered Chelsea's demise on Saturday. Just how Middlesbrough winning can help Portsmouth's position is beyond comprehension.

As for United, this was a day that sustained their fragile title ambitions. "We have not given up hope of catching Chelsea," said van Nistelrooy. "But we will have to continue playing as we did in the first half and Chelsea will have to collapse."

On Saturday second top against second bottom looked exactly that. Portsmouth were surprisingly subdued in the first half, when the class of van Nistelrooy and Ryan Giggs underpinned United's superiority and put them 3-0 ahead.

Then there was Ronaldo, so often accused of being little more than an adornment but clearly a player of substance as well as style.

Van Nistelrooy had nodded United ahead in the 19th minute after a thrilling run by Giggs had ended with a left-foot shot that saw the ball rebound from the underside of the bar.

Then Ronaldo scored with a fierce and swerving shot that passed through Dean Kiely's hands.

Ronaldo scored again, his second double in a week, just before half-time, after being put through by Wayne Rooney, who had another quiet game and showed his displeasure at being substituted by flinging his shinpads to the ground.

Portsmouth had beaten United on their previous two visits to Fratton Park; it was never going to be a hat-trick.