Wild celebrations greeted another slender Manchester United victory at Old Trafford last night although this time Gary Neville was a model of decorum as the home supporters and Sir Alex Ferguson reacted to confirmation of a place in the Carling Cup Final as though their futures rested on it. In many respects, of course, it did.

The elevation of the Carling Cup in United's list of priorities emphasises the diminishing returns for Ferguson, but having heralded the competition as "a great opportunity to mark this season as a successful one" the performance of his team against a Blackburn Rovers side low on strikers but high on endeavour proved the 64-year-old Scot still has the capacity to leave his players hanging on his every word. United shone only in parts yet fought for the right to face Wigan in the all-Lancashire final throughout the semi-final second leg, though perhaps too literally during the interval.

While goals from Ruud Van Nistelrooy and Louis Saha secured their date at the Millennium Stadium, several of their players, notably Rio Ferdinand, could be set for an appearance before the FA's disciplinary committee after an alleged brawl involving, surprise, surprise, Blackburn's Robbie Savage on the way down the Old Trafford tunnel. Though both managers attempted to downplay the incident afterwards, and in fairness they were still out on the pitch while every outfield player sprinted to take part in a melée witnessed by hundreds of supporters, the sight of two shadow-boxing ball-boys near the entrance to the dressing rooms gave the game away.

"As he was on his way to the dressing room, Rio clipped Robbie," said the Rovers manager Mark Hughes. "I don't know why he did it, but there was no need. Robbie then asked him why he had done it and everyone else ran in just to make sure nothing happened." Television evidence, which was not replayed by Sky, could yet prove if that was the case. Should the FA launch an investigation into what occurred, then it should not overlook the contribution of referee Graham Poll towards the simmering passions of the players, especially those of a Blackburn hue.

The Tring official harshly penalised Zurab Khizanishvili for deliberate handball inside his own penalty area two minutes before the break, and then allowed Ferdinand to escape with a similar offence in the second half, but it was the decision not to punish Van Nistelrooy for venting the frustration of seeing his spot-kick saved by Brad Friedel on the heels of Steven Reid and into the back of Savage that left the visitors enraged.

Hughes admitted: "A number of decisions led to frustration on our part. There are only so many Premier League referees and some are achieving a celebrity status and that is dangerous - 61,000 people came to watch two teams play but Mr Poll thought they had come to see him."

In fact, the majority of the Old Trafford crowd had come to witness United move closer to restoring some pride from this season. In that respect, Wayne Rooney and a contest that almost equalled the previous evening's semi-final at Highbury for entertainment did not disappoint.

Rooney was afforded even more licence to roam than usual on account of a depleted United midfield that left Ferguson no option but to field a three-pronged attack. He helped create the eighth-minute breakthrough for Van Nistelrooy, albeit with the aid of a generous ricochet off Michael Gray after a typical run from deep, and the fortunate goal that settled the tie six minutes after the restart when Saha sliced his fifth Carling Cup goal in four games beyond the outstanding Friedel.

Unfortunately for the United number eight, his team-mates do not possess his consistency nor his manager the midfield to dominate an improving team like Blackburn and they allowed Reid to deservedly level in the 32nd minute when Kieran Richardson made a complete hash of a clearance from Morten Gamst Pedersen's cross.

"I told the players at half-time that they had to join in the cup tie otherwise they would be left with regrets," said Ferguson. "But they responded well. They matched Blackburn's work-rate in the second half and it is great to be going to Cardiff again."

Even in this extended transitional phase at Old Trafford, Ferguson could never have envisaged his season being rescued by the competition he once treated as a breeding ground for his club's Academy.

"I owe Manchester United my foresight," he declared before kick-off.

"I am not going to leave this club in a shambles when I go. They have been too good to me for that. The manager who follows me will find that he inherits a squad in good shape, with quality players. However, that's for the future."

And he can delay the issue of his abdication even longer if he triumphs on 26 February.

Manchester United (4-4-2): Van der Sar; Neville, Ferdinand, Brown, Evra (Silvestre, 79); Rooney, Fletcher, Giggs (Smith, 13), Richardson; Saha, Van Nistelrooy (Vidic, 85). Substitutes not used: Howard (gk), Rossi.

Blackburn Rovers (4-4-2): Friedel; Neill, Nelsen, Khizanishvili, Gray; Reid, Savage, Tugay (Peter, 85), Pedersen; Kuqi (Emerton, 76), Bentley. Substitutes not used: Enckelman (gk), Todd, Mokoena.

Referee: G Poll (Hertfordshire).