Manchester United 2 Blackburn Rovers 0: Ronaldo's two-minute warning

"You're starting to sound like Ronaldo," Sir Alex Ferguson quipped last week when it was put to him that his side might, on current form, be the best in Europe. If the Portuguese is his dressing room's arch-optimist then he may also prove to be the talisman for as long as it takes Wayne Rooney to recover from his collision with training equipment during another exuberant training session.

The Portuguese has never scored a hat-trick for United and Rio Ferdinand gently reminded him during the second half here, with Rovers reduced to 10 men, that this might be the day for him to improve on the 10 two-goal strikes he has managed for the club. It was not to be, but Ronaldo, now United's leading scorer in the league, could afford to be philosophical about that on an afternoon in which Rooney's talents were at times sorely missed.

Ronaldo said with customary self-confidence that the header with which he sent United ahead on 31 minutes was "a fantastic jump" and he was right. It was a classic centre-forward's strike, enough to have his manager agreeing that he might need to be deployed in that role until Rooney returns in four weeks. The second goal was equally well executed: a beautifully weighted shot across Brad Friedel after Carlos Tevez, sent through by Louis Saha, supplied him with the outside of his right foot. It was some cameo – two goals in as many minutes – and it finished the game off, long before the unworthy dismissal of David Dunn on 52 minutes reduced the second half to a formality.

The absence of an obvious striking replacement for Rooney makes Ronaldo's importance to Ferguson all the greater. Saha, starting for the first time in the league, was a shadow of the first-choice penalty box protagonist and his performance here will have done little to alter his manager's view that he is of most value in a substitute's role.

Blackburn, who arrived here with seven wins and the draw against Liverpool behind them, expected a point and their performance illustrated why Ferguson considers them, more than Everton, Portsmouth or Manchester City, likely to claim a place in the top four.

Their defence occasionally strayed into the realms of the agricultural, but Ryan Nelsen and Christopher Samba snuffed out United's threat in a way that few teams have managed. After Tevez had spurned a couple of early opportunities in the first 10 minutes – firing over after Ronaldo had headed down Wes Brown's cross and forcing one of several good saves from Friedel – Hughes' side created just as many chances as United.

The Norwegian Morten Gamst Pedersen, with memories of scoring twice when Rovers won here two seasons ago, placed a shot just wide and had a shot blocked after finding space to shoot in a crowded United box. A turning point arrived when Dunn dispossessed Ronaldo as he attempted to dribble from his box and provided Samba, whose shot rattled against the bar. "If that had gone in, it could have been different," a rueful Hughes later reflected.

It was the third time in two weeks that Rovers had found the woodwork in the first half and there were more echoes of last week's game against Liverpool when David Bentley cleared off the line on the half-hour. But Bentley should have known this was not his day. The printers had misspelt his name on his match shirt and when Betnley – as he had become for the day – tried a second goal-line clearance when Rovers failed to mark Ronaldo from Giggs's corner, he could only divert the ball into his own net.

Hughes had warned Rovers after their capitulation to Larissa in the Uefa Cup, about the dangers of conceding twice in quick succession. "We didn't learn," he said.

His side might have made more of the second half, were it not for the dismissal of Dunn. His first booking, for a challenge on Tevez, seemed soft and even Ferguson admitted that the tackle on Saha which presaged his exit was unlucky.

It meant that the best second-half chances belonged to United. Ronaldo fired over on the hour and Brown, influential down the right, provided Giggs with a chance that was blocked. But the impressive first-half creative play of Bentley and Benni McCarthy was curtailed.

Ferguson described the current United squad as his "strongest ever" on the day they went back to the top of the table. "This is what I have been working towards. I don't like the short-term fix. I prefer to see a pool of players emerge and develop into something special." With Bolton, Fulham and Derby in United's path after the international break, Arsenal will need to be on their mettle to regain the ascendancy.

Goals: Ronaldo, 36 (1-0) Ronaldo, 37 (2-0).

Manchester United (4-4-2): Van der Sar; Brown, Vidic, Ferdinand, Evra; Ronaldo, Hargreaves (Carrick, 76), Anderson, Giggs; Saha (Nani, 66) Tevez. Substitutes not used: O'Shea, Fletcher, Kuszczak (gk).

Blackburn Rovers (4-4-1-1): Friedel; Emerton, Samba, Nelsen, Warnock; Bentley, Dunn, Pedersen; McCarthy; Santa Cruz (Derbyshire, 78). Substitutes not used: Ooijer, Tugay, Berner, Brown (gk).

Referee: C Foy (Merseyside).

Bookings: Manchester United Ronaldo. Blackburn Rovers Dunn, Mokoena, Nelsen, Samba. Sent off: Dunn.

Man of the match: Ronaldo.

Attendance: 75,710.