In the final moments of this utterly one-sided encounter, as the temperature dropped below freezing and the mist rolled in off the Solent, the name of the late Bobby Stokes briefly resonated around this soulless, lifeless arena. At first it sounded like defiance on the part of the Southampton supporters, but in reality it was something closer to desperation as they sought to remind the world and above all themselves of a time when they could take on and beat the mighty Manchester United.

That time has rarely felt as distant as it did yesterday, a day, an afternoon when the harsh realities of 21st-century football bit far harder on the South Coast than the cold snap. Southampton remained competitive for many years after Stokes’s goal beat United in the 1976 FA Cup final at Wembley and it is only 3½ years since their proud top-flight status was surrendered, but, for all that, it may as well be a different lifetime.

FA Cup third-round weekend is a time for dreaming, but the mood in Southampton was best summed up by one of the club’s stewards, who was telling anyone who would listen beforehand that United, even without Rio Ferdinand, Cristiano Ronaldo and others, would win by “at least four goals”. As it was, United settled for three, scored by Danny Welbeck, their promising young forward, Nani, the beneficiary of a bizarre penalty award, and finally Darron Gibson, a substitute.

Jan Poortvliet, the Southampton head coach, believed that Welbeck’s goal was offside and that the penalty should not have been given — and that was before he invited an FA misconduct charge by accusing Mike Riley, the referee, of “helping the big teams” by sending off Matthew Paterson for an ill-timed lunge on Nemanja Vidic in the 36th minute. But the sense of injustice cannot be allowed to fester too long at St Mary’s. The stakes are too high as Southampton battle to avoid slipping farther into oblivion, faced with the threat of relegation to the third tier of English football for the first time since 1960.

There is a temptation to characterise contests such as these as men against boys. It certainly looked that way for long periods, with Southampton’s raw youngsters struggling to live with the grace and the poise of Michael Carrick, Ryan Giggs and Dimitar Berbatov, but upon closer inspection it was not quite as straightforward as that. Southampton’s best two performers — the duo who spared their young team-mates from the kind of mauling that would have left an even greater dent in their confidence — were Kelvin Davis, the 32-year-old goalkeeper, and Chris Perry, the 35-year-old defender. United’s goalscorers were aged 18, 22 and 21. The United midfield was run for much of the second half by Gibson, Anderson, 20, and Rodrigo Possebon, 19. It was not a question of age. It was one of maturity and, above all, composure.

That being the case, Southampton’s supporters must rue the fact that their slim hopes were pinned on the broad but inexperienced young shoulders of Paterson, a 19-year-old who, in only the second full appearance of his professional career, was caught up in the occasion and succeeded only in shooting himself and his team in the foot. Less than 60 seconds had gone when he caught Jonny Evans, the United centre half, long after the ball had gone. A yellow card at that point “might have calmed him down”, according to Sir Alex Ferguson, but the teenager continued, undeterred, and earned his marching orders nine minutes before half-time when he caught Vidic with the type of wild challenge that is simply not allowed in the modern game.

By that stage United were already 1-0 up, Welbeck underlining his growing promise with a close-range finish after John O’Shea’s header was pushed on to the crossbar by Davis. Poortvliet complained afterwards that the United forward had been in an offside position when O’Shea headed the ball. On further examination, he had a point, but, if there was one legitimate ground for complaint for Southampton, it came early in the second half, when Nani’s free kick struck the head — not the hand — of David McGoldrick in the defensive wall. Riley pointed to the penalty spot and Nani, in Ronaldo’s absence, eagerly seized the responsibility of taking the kick, which he sent past Davies.

By now United were coasting, the more so after Rooney was brought on alongside the excellent Berbatov. Gibson made it 3-0 with nine minutes remaining, lashing the ball past Davis after being set up by Rooney.

It was then that the Southampton supporters began to sing paeans to Stokes, harking back to 1976 and to the happier times at The Dell, their former home. That has long since been demolished, making way for a housing estate. St Mary’s was designed to take the club into the 21st century. The sad truth is that Southampton were happy where they were.

Southampton (4-4-1-1): K Davis 8 - L James 5, O Lancashire 7, C Perry 8, R Skacel 4 - R Smith 6, A Surman 6, S Gillett 4, O Gobern 4 - D McGoldrick 6 - M Paterson 2. Substitutes: M Schneiderlin 5 (for Gillett, 56min), K McLaggon 5 (for Gobern, 56), L Holmes 4 (for Smith, 70). Not used: T Forecast, L Molyneux, J Euell, B Wright-Phillips.

Manchester United (4-4-2): E van der Sar 6 - G Neville 7, N Vidic 7, J Evans 5, J O’Shea 5 - Nani 7, M Carrick 7, R Giggs 6, Anderson 6 - D Berbatov 8, D Welbeck 7. Substitutes: D Gibson 6 (for Carrick, 57min), R Possebon 5 (for Giggs, 57), W Rooney 7 (for Welbeck, 64). Not used: T Kuszczak, Rafael Da Silva, D Fletcher, Park Ji Sung.

Referee: M Riley Attendance: 31,901