THE toughest job at Old Trafford on Saturday fell to the oldest man on the pitch.

Colin Cooper, veteran of nigh on 600 league games for five clubs, was given the unenviable task of shackling the player dubbed the biggest star of his generation - Wayne Rooney.

It was a challenge the soon-to-be 38-year-old accepted manfully and on a number of occasions proved that experience does have the edge over youth.

However, when it counted, the Boro stalwart was undone by the prodigy young enough to be his son.

Not that Rooney's impudent strikes were in any way, shape or form down to mistakes on Cooper's part, because despite the platitudes paid to the team in some circles, Boro just didn't put up a fight.

Both the forward and midfield lines should hold their hands up for a dereliction of duty that meant Cooper and his defensive team-mates of Gareth Southgate, Michael Reiziger and Franck Queudrue were seldom able to clear their lines or their heads.

Manchester United pressed from the off and Cooper, likely to be the fall guy if and when Bobo Balde arrives from Celtic, was soon in the thick of the action facing a three-pronged assault from Rooney, Ryan Giggs and Cristiano Ronaldo.

There are few that would look forward to that prospect, but by his animated gestures you got the feeling Cooper was revelling in the opportunity to test himself as the twilight of his career approaches.

"If you looked at it and somebody of Colin's age was performing as well as he is in the Premier League, then perhaps you would be surprised," Southgate said after the league game at Norwich recently.

"But knowing the guy and the character that he is and how fit he is, then no, I am not surprised because he has proved it time after time when he has come into the team."

It's hard to disagree, especially on Saturday's evidence.

With five minutes gone he rose in the box to head a Giggs cross away from the lurking Rooney and the tone was set for the evening.

Boro were under the cosh and when it wasn't Rooney looking to find an opening Giggs and Ronaldo were there to offer their own threat.

It must have been a surprise then to Cooper and the vast majority of those inside the so-called Theatre of Dreams when United opened the scoring through John O'Shea ten minutes in.

Intent on ensuring Rooney didn't get a look in when Ronaldo won possession inside the box, Cooper and co gave the O'Shea time and space to control the Portuguese's deflected pass before firing past Mark Schwarzer.

It took fully 17 minutes for Boro to have their first attack but Cooper barely had time to catch his breath before he was facing up to another onslaught.

After he and Queudrue thwarted a mazy Giggs run, Cooper must have been relieved to see his goalkeeper turn a Rooney shot around the post after the England striker broke free on the left edge of the area.

He redeemed himself minutes later though when he made a measured tackle to deny Rooney another chance after he shaped to shoot.

If Cooper thought Boro boss Steve McClaren's half-time team-talk might spark some attacking life into the side and give his ageing legs some respite he was sadly mistaken.

Giggs made way for Louis Saha and within two minutes United doubled their lead.

Rooney turned away from Cooper and with Schwarzer haring off his line the former Everton man produced an exquisite lob to end any chance of a fightback.

Cooper knew exactly what Rooney had in mind as the keeper advanced from goal but his cries of 'get back, get back' were in vain and he could only stand and watch a piece of pure unadulterated genius.

Cooper's last involvement in the game saw him move smartly to deny Saha an opportunity in front of goal and so with 11 minutes left he was replaced by Tony McMahon.

It was an understandable decision given Cooper's flagging energy reserves, but, with all due respect to McMahon, it only served to weaken arguably Boro's strongest link on the day.

Not that he nor anyone else could have prevented Rooney's second and United's third, a fierce volley that rocketed into the roof of Schwarzer's net eight minutes from time.

Boro make the trip to Portsmouth tomorrow and if the Balde deal goes through Cooper is likely to find himself on the bench at best.

There are few that would begrudge him a chance to put his feet up and take it easy but you can guarantee he would jump at the chance to get out there again.

At least the only time he will see Rooney again this season is on Match of the Day.

Read more about Middlesbrough here.