There have been few more surreal moments at Old Trafford than spotting Roy Keane, sitting alone apart from his young son, two rows away from Noel Edmonds in the directors' box. But then Saturday was not a day which made much sense to anyone who follows football, and least of all to those who are still trying to understand how some of Sir Alex Ferguson's players can claim to be worthy of Manchester United.
It was a good day for Noel Edmonds, though. The deposed king of Saturday night television is an adopted Devonian who, having earlier announced his divorce in the tabloids, grinned his way through a superb Exeter performance. Keane was impassive and, no doubt, deeply unimpressed by the prospect of a trip down to St James Park on 18 January to sort this mess out. Regardless of the side that United fielded, this was an absurd and embarrassing result for the FA Cup holders, which Ferguson described as the "worst cup performance" in his 18 years in charge.
If there has been a worse performance than this one in any competition then it must have been atrocious. The United manager stalked off alone to the tunnel when the final whistle sounded. He will have got back sooner than the Exeter players who later lined up outside the home dressing-room to get the souvenirs they had bought in the stadium megastore signed by United's players. It was telling that it took the end of the match, rather than the start of it, to emphasise the disparities between the lives of these two sets of footballers.
But before any discussion of United's guilty men, it is important to identify those in the Exeter side who excelled beyond all expectation. Dean Moxey, the match-winner against Doncaster in the previous round, was tireless. Andy Taylor, a classy midfielder who was rejected by United as a schoolboy, was inspirational. At 22 he has fought his way back from a serious knee injury, via part-time football at Northwich Victoria, to establish himself in his home-town side.
None of them quite topped the performance of the goalkeeper Paul Jones, a shy, awkward 18-year-old who shares little in common with United's £12m teenager Cristiano Ronaldo other than the lingering remains of adolescent acne. On loan from Leyton Orient, he discovered only on Thursday he was to play and, on 77 minutes, brilliantly palmed away a drive from United's Portuguese winger. Like so many of the Conference side's players he was rejected from a Premiership club - Charlton - and is rebuilding his career.
The goalkeeper stopped short of saying that the second-string side Ferguson picked showed little respect towards Exeter but he did add that United are likely to take the replay at St James Park a "step more seriously". Jones did not hide his delight at bagging Tim Howard's United shirt, but this childhood Chelsea fan made a valuable point about the side he had just faced. "If they put a team out like that against Chelsea in the Carling Cup," he said, "then they'll be destroyed."
That is a question Ferguson will have to ponder this morning, although the Carling Cup might just be the least of his worries. On Saturday, Eric Djemba Djemba, Liam Miller and David Bellion were astonishingly poor. The Cameroonian struggled to direct a single pass to a team-mate while Miller was bullied out of the game by Exeter's brisk, physical style. Virtually alone in attack, Bellion posed pitifully little threat.
Those three, as well as Kieran Richardson, Chris Eagles, Jonathan Spector and David Jones are, we are constantly told, United's next generation of players. Not on this evidence. There have been hints at their inadequacies when Ferguson has picked weaker teams for dead rubbers in the Champions' League in the last two years but nothing quite as damning as this.
There were occasions when Exeter very nearly scored, not least when Taylor's free-kick before half-time just curled past the post. Moxey volleyed over before the hour and then the onslaught began as Ferguson was forced to introduce Paul Scholes, Ronaldo and finally Alan Smith. The former Leeds striker's first job was to collar the Portuguese winger and tell him, in no uncertain terms, to stop stepping over the ball and start crossing it into the box.
It was frantic for Exeter at the end of the game and Scholes almost snatched an undeserved win with a turn and shot that dribbled just wide of the post on 92 minutes. But Exeter hung on to return to their dressing-room to discover that they had each been given an entire United strip. It was a classy gesture by Ferguson, who also invited the Exeter manager, Alex Inglethorpe, 33, in for the traditional post-match glass of red.
"Sir Alex was very complimentary," he said. "I always knew if we had a good start we would gain confidence." In the end, the overwhelming sense was not of Exeter's over-achievement, but that Ferguson had been badly let down. Eight Premiership titles, a European Cup and 30 years in management are supposed to protect you against humiliations like this. He has shown faith in this group of young players and now has to take a senior side, tired by the Christmas programme, to Exeter to try to finish the job. For a few of United's players, it felt like their long goodbye from Old Trafford started on Saturday.
Manchester United (4-5-1): Howard; P Neville, Pique, Brown, Spector; Eagles (Scholes, 63), Jones, Djemba Djemba, Miller (Ronaldo, 63), Richardson; Bellion (Smith, 76). Substitutes not used: Heinze, Ricardo (gk).
Exeter City (4-4-1-1): Jones; Hiley, Sawyer, Gaia, Jeannin; Taylor (Edwards, 89), Clay (Ampadu, 66), Martin, Moxey; Flack (Afful, 74); Devine. Substitutes not used: Rice (gk), Sheldon.
Referee: P Dowd (Staffordshire).
Man of the match: Paul Jones.
Attendance: 67,551.Reuse content