Watford 1 Manchester Utd 4:As Rio Ferdinand recalled his earliest FA Cup memories, waxed lyrical about the shirt John Barnes gave him as a memento from Liverpool's 1988 final and laughed at the notion Wayne Rooney has been suffering from a loss of form this season, it became clear that the injury which forced the Manchester United defender to leave the field against Watford before half-time was not the setback Alex Ferguson may have first feared.

Having been unable to conceal his frustration as he departed in the 40th minute, Ferdinand was in sanguine mood afterwards, suggesting he would probably miss tomorrow night's match with Sheffield United but could be fit for Middlesbrough on Saturday. The England defender was due to have a scan on his groin yesterday but there was no sense of foreboding about the results. "I came off as a precaution to make sure I didn't aggravate it," he said.

With Nemanja Vidic sidelined with a broken collarbone and Gary Neville feeling his way back from an ankle problem - the full back could feature against Middlesbrough - news that Ferdinand is unlikely to have sustained any serious damage will be greeted with relief by Ferguson. Milan come to Old Trafford next week and then the United manager cannot contemplate placing square pegs in round holes as he did here.

Ferguson claimed he was "down to the bare bones" after United secured a place in the FA Cup final, his case more than supported by the presence of a makeshift back-four which finished with Darren Fletcher at right back and Gabriel Heinze, deputising for Ferdinand, playing alongside Wes Brown in central defence. Watford, spirited but limited, were unable to expose those limitations. Milan, despite their ageing limbs, would surely be less forgiving.

Indeed United's rearguard is the one department in Ferguson's team that opponents may view with encouragement. Watford's goal here, wonderfully taken by Hameur Bouazza as he steered an acrobatic volley past Edwin van der Sar, means United have kept one clean sheet in their last six matches. That statistic would be more unsettling for Ferguson were his players not tearing into opponents at the other end of the pitch with such jaw-dropping brilliance.

Ferguson's team appear to be approaching the defining period of their season with a swagger, Rooney declaring in the wake of this victory that United have never performed at such a level during his time at the club.

"People were writing this team off 18 months ago but we knew we had a lot of young players who were going to get better as they matured," he said.

Few would claim Rooney has shown tangible improvement during that period, having spent this season very much in Cristiano Ronaldo's shadow, but the England striker's performance on Saturday carried that wonderful amalgam of skill and determination that had been so prominent during his teenage years.

"Rooney had his best game of the season, he was absolutely fantastic," said Ferguson.

Nothing captured those attributes more than his part in the second goal when he showed remarkable tenacity to outjump Jordan Stewart on the touchline before having the presence of mind to pick out Ronaldo with a measured cross. It was as if Rooney had considered it a personal affront that Bouazza should dare cancel out his opening goal, the equaliser coming two minutes before Ronaldo's goal.

Watford were powerless. "You can't stop those guys; all you can hope for is to try to contain them," said Jay DeMerit, reflecting on Rooney's and Ronaldo's threat. "They used to say that about Michael Jordan back in the States. They (Rooney and Ronaldo) are the same type of players. They come at you from all angles and make life very difficult. They will always create opportunities for themselves because of the qualities they have."

It is the kind of service that Michael Owen, reported to be attracting United's interest as he continues his rehabilitation, would surely welcome. Not that the absence of a predator is glaring at the moment, with Kieran Richardson, making the most of his second-half introduction, converting United's fourth goal after Rooney had tapped in Alan Smith's searching cross for the third. ... Guardian Service