DERBY, England (AFP) - Cristiano Ronaldo spared Manchester United major embarrassment with the goal that secured a 1-0 victory over virtually relegated Derby County at Pride Park on Saturday.

The Portuguese international cut a sullen and almost tearful figure at times as he squandered eight opportunities of his own, on what was a dreadfully frustrating day for Sir Alex Ferguson's side.

But, as so often this season, the talent that has lit up the title race proved telling and Ronaldo struck to secure victory 15 minutes from time.

Ronaldo's 31st goal of an incredible season could yet prove to be one of the most significant, on a day when United created more chances in 90 minutes than Derby have managed all season.

Ferguson was forced to make three second half substitutions to try to shake up his mis-firing side as he saw precious title points slipping away - on a day when United were expected to coast to victory.

Instead Ronaldo's volley from Wayne Rooney's pass in the 75th minute finally defeated Roy Carroll as Derby restored some much needed pride to a miserable season - after being challenged by manager Paul Jewell to at least go and stand toe-to-toe with the Champions.

They did exactly that to at least give some hope for the future and Ferguson will be a hugely relieved man after such an incredible struggle to beat the side that has been heading back to the Championship virtually since the start of the season.

Derby, humiliated by six Chelsea goals at Stamford Bridge in midweek, could easily have conceded the same number within 30 minutes as they were simply over-ran and out-manoeuvred by United's supremacy in all departments.

No wonder Jewell cannot wait for the season to end as he was made to squirm with embarrassment by the huge gulf in class between his own side and the Premier League holders.

Ronaldo set the tone for a frustrating first half from the third minute, shooting wide, following Patrice Evra's pass, as well as striking the post from John O'Shea's cross, as former United keeper Roy Carroll lived a charmed life.

Ryan Giggs was equally careless with his finishing, lifting another effort high and wide and then failing to convert Wayne Rooney's wonderful reverse pass after rounding Carroll.

The Northern Ireland international then produced an acrobatic save to prevent Ronaldo's shot with the outside of his right foot finding the top corner.

United's benevolence could easily have left them with faces as crimson as their shirts, but fortunately Ben Foster, making his Manchester United debut, justified the claims of manager Sir Alex Ferguson that he is a certainty to be England's goalkeeper in the future.

The 19-year-old, back from a cruciate ligament injury suffered in June last year, showed superb levels of concentration, after spending the first half-an-hour as a complete spectator, to produce full length save to repel Mile Sterjovskis volley.

Scottish international Kenny Miller was also foiled with another excellent save, after Robert Earnshaw sent him beyond Nemanja Vidic, to expose the United youngster and Foster had to produce another fingertip save late on to prevent Sterjovski's shot from looping high into the net.

Ronaldo still had time to force two more excellent saves from Carroll, which would have made the score more acceptable for Ferguson, but he was unable to add to his own personal tally.