Manchester United's manager Sir Alex Ferguson had mixed feelings following the latest win over Birmingham City.
He saw his team struggle in the first half but battle back to snatch the points with second-half goals from Ronaldo and Louis Saha when United turned up the heat on a luckless City.
Birmingham had every reason to be disappointed with the result after producing a fine performance but they were beaten by a United side which struggled for a long time to get into gear.
United lifted themselves in the second half and are now on course to finish runners-up to Arsenal, but Birmingham are now concerned that their season could finish on a sour note.
Birmingham, who last beat Manchester United at Old Trafford in 1978-1979, had high hopes, but eventually had to concede defeat following some indifferent defensive work.
Steve Bruce, Birmingham's manager, admitted: "We are disappointed with the result. To concede two goals from two crosses sent in from 40 yards out is particularly disappointing.
"But that is what it is all about playing at this level. It was two lapses of concentration and we were punished.
"Adding to our problems is that Stan Lazaridis and Martin Grainger will not be fit to play again this season. Lazaridis has a groin injury and Grainger has damaged his knee again.
"We are now down the bare bones and that is now going against us.
"I thought we were magnificent in the first half. We gave a terrific display and could have been two goals ahead at half-time.
"But when you play the top teams you have to keep playing for 90 minutes as United proved again on this occasion.
"We expected to defend better than we did on this occasion. Ronaldo is a terrific player who is going to get even better.
"That is the difference between the likes of Birmingham and Manchester United. Unfortunately it cost us at the end of the day.
"What we need is a victory to push us on against one of the top clubs. If we had beaten United it would have been a terrific boost." From the high of defeating Arsenal in the FA Cup semi-final Manchester United returned to their routine league programme in the full knowledge that they cannot now make up the Premiership leeway on the Gunners.
In the absence of Roy Keane and Ruud Van Nistelrooy the Old Trafford club were an ordinary looking team in the first half as Birmingham, showing commitment and endeavour, battled bravely to take the game to the opposition and were justifiably rewarded when substitute Martin Grainger gave them the lead from 37th minute direct from a free-kick.
But the unfortunate Grainger, who has been plagued with injuries over the last 18 months, failed to appear for the second half when he too was replaced by Jamie Clapham.
In the pre-match rumbles Birmingham manager, Steve Bruce, claimed that the often controversial Robbie Savage had been "stitched-up" by the national press for his adverse comments about Manchester United.
Unfortunately Birmingham have been at logger-heads with the media generally over the last few days involving David Dunn when it was wrongly claimed that he was thinking of quitting the game and also the reported lack of ground security.
Birmingham responded to this outburst of adverse publicity by banning all their players speaking to the press before and after the game.
As a result of this impasse relations have hit a very low level which is a great pity during what has been an outstanding season for Birmingham.
Savage was apparently not put out of his stride by events of the last few days as he was obviously determined to make an impact against one of his old clubs.
His all-out action did not please United manager Ferguson, who was concerned that Savage was often winning most of his tackles and in the process putting the Old Trafford side out of their stride.
Birmingham, however, suffered a set-back as early as the 12th minute when Lazaridis was stretchered off after turning awkwardly following a tackle by Paul Scholes.
Grainger, recently recalled from his on-loan spell at Coventry, responded by adding extra power to the Birmingham attack which surprisingly posed problems for United's defence.
Bryan Hughes tested Roy Carroll after being put clear by Mikael Forssell, while Stephen Clemence wasted a good opportunity with United's defence on the wrong foot from Savage's free-kick.
In sharp contrast United failed to have a single shot on or off target in a lacklustre first half and could have had few complaints when they went into arrears in the 37th minute.
Savage, who had earlier hit the crossbar with a speculative shot, won a free-kick in an incident involving Scholes. But it was Grainger who hammered his shot into the roof of the net.
United lifted their game in the second half and it corresponded with the belated introduction of Ronaldo.
In the 56th minute a Ryan Giggs cross was flicked on to Louis Saha to see his header flicked over the bar by Maik Taylor.
Inspired by this effort a minute later Giggs floated over a cross which the purposeful Ronaldo headed past Taylor for United's equaliser as they posted their intentions to put Birmingham under greater pressure than in the first half.
United had their chances to have ripped Birmingham apart and no-one more so than Saha. The little striker, recruited from Fulham, came alive in the second period.
Kenny Cunningham, who had kept Saha in his pocket for the opening 45 minutes, suddenly found the Frenchman a different proposition.
Although he failed to take advantage of a bad clearance by Matt Upson and then saw a shot blocked by Martin Taylor he could not be denied and put United ahead in the 78th minute with a flashing header from a Giggs free-kick on the right.
Man of the Match: Cristiano Ronaldo - demonstrated his class when Sir Alex Ferguson sent him on early in the second half. His pace and skill lifted United out of the doldrums and transformed their performance.