Far from being overawed by the 74,000 crowd, Iain Dowie's men rose to the occasion and two Michael Mifsud goals swept them into the last 16.

It was the second successive year Sir Alex Ferguson's men had tumbled out to lower league opposition, after a similarly embarrassing defeat to Southend at Roots Hall last year.

The defeat also marked the first time United had lost to lower league opposition at Old Trafford since now non-league York City trounced a side containing Ryan Giggs and David Beckham 12 years ago.

Ferguson was quick to express his dismay afterwards. In his programme notes, the United manager spoke in glowing terms about the players he was selecting, rounding off with the somewhat embarrassing pay-off line 'sit back and watch the emergence of some very special talent'.

So the Scot was simply unable to comprehend why a team containing internationals at the start, including $85million new boys Nani and Anderson, plus another two in Michael Carrick and Wes Brown by the end, failed to impose themselves on a team hammered by Ipswich only five days earlier.

It certainly was not the night O'Shea would have wished for as he returned from a two-week absence with a knee injury to take the captain's armband.

But the Irishman admitted United got exactly what they deserved.

"The lads know they should have done better," he said.

"For some reason, the technique and ability we know these young players have just wasn't there, which was a big disappointment.

"Coventry just seemed to get on top of us and we didn't manage to get that lucky break, or a goal that would have settled everyone down.

"Even if we had clawed it back, it would have been unfair on Coventry. They were better than us and they deserved to win."

Having taken a strategic decision to keep most of his young players at Old Trafford this season rather than send them out on loan as has been the case in previous seasons, Ferguson now faces a dilemma.

It remains to be seen whether this defeat will mark the end of any United careers, as the Southend loss did for David Jones and, eventually, Kieran Richardson last term.

Most of those involved last night would appear to have some kind of United future, maybe with the exception of Phil Bardsley, a one-time contender to replace Gary Neville in the senior ranks, but whose removal at half-time suggested the depth of Ferguson's displeasure.

Improvement is vital though, particularly in the case of Dong Fangzhou, who remains more important as a commercial tool than a player.

Nani and Anderson, for all their youth, will also have to do much more to convince Ferguson he can cope without Ryan Giggs and Paul Scholes for anything more than the odd game.

Spanish defender Gerard Pique admitted the sight of Coventry's success beaming down at them from scoreboards at either end of the ground was 'horrible'.

"Some people will think we have missed our chance," he reflected.

Undoubtedly, there are a few tarnished reputations to clean up, not least Jonny Evans, who was so impressive at Sunderland last season but struggled to cope as Mifsud buzzed around.

But, as Giggs and Beckham can testify, one defeat in the League Cup - however humiliating - does not necessarily signal the end.

"In cup ties like this, you have to put opposition defences under pressure and create chances," said O'Shea. "We just did not do that.

"Obviously, the manager learns a lot more from the players in games like this.

"But these players do have quality. All we can do now is try to bounce back, make sure we work hard in training and put pressure on the lads in the first team."