Guidetti lets United off the hook in late drama
Manchester utd 1-1 Celta Vigo (Man United win 2-1 on agg)
Manchester United's long march through the 15 games of the modern format of the Europa League is just one from completion but it has been fraught and laboured and the chaos that engulfed the end of this one will tell Jose Mourinho that nothing can be taken for granted at the final in Stockholm this month.
A late equaliser conceded and then the anxiety taking hold of United's players with Eric Bailly sent off for a hand to the throat of a Celta Vigo opponent and Antonio Valencia lucky not to go the same way for the shove that followed.
United will miss Bailly in the final against Ajax on May 24 in the Friends Arena and how United made such hard work of beating the team placed 12th in La Liga only they will know.
Another draw for the specialists in the art and a tie that they should have been out of sight in taken right to the death by an opposition who were in it for every one of the nerve-wracking six minutes added on by the Romanian referee at the end of the game.
United are in the Europa League final, and Mourinho will point out it is their second final of the season, although they will have to beat the competition's form team to win it.
This was not a United European semi-final in the tradition of those great occasions when they eliminated Juventus in 1999 or Barcelona in 2008, rather it was a narrow squeak past the team placed 12th in La Liga who would have been blitzed by previous Old Trafford sides.
The Champions League place is within United's grasp although it would not have been the case if Celta had a striker who could bury his chances.
The miss in the last moment of the game by the former Manchester City academy boy John Guidetti will live with him forever and at the end the players of a very ordinary Celta side lay on the pitch in despair at a game they thought they could win.
For the biggest game in their history, this United team started tentatively and it was a good 10 minutes before they woke up to their manager's interpretation of this game's importance in 139 years of the club's existence. It was only then they got a grip and the goal after 17 minutes was dispiriting for the away side.
Celta arrived at Old Trafford on a five-game losing streak, including the first leg of this semi-final the week previous, and very little to lose by attacking.
In the opening stages they tried to exploit the space in behind Matteo Darmian with early balls hit into that area for Iago Aspas to run on to.
They even had a bit of joy when the former Liverpool man cut back on his left foot and forced a save from Sergio Romero.
In those early stages, there was the worst of Mourinho's United - reactive, and unwilling to take hold of possession but eventually they came into the game, led it should be said by Paul Pogba.
His agent might be richer than him but no one matches his physicality when the Frenchman is on his game and the way in which he muscled in Nemanja Radoja on 11 minutes demonstrated his strengths.
On that occasion Pogba could not get Rashford away but the teenager's pace and willingness to stretch Celta was a constant worry for the visitors. It was another aspect of Rashford's game that was conspicuous on 17 minutes when he took the ball on the left, looked up and struck a brilliant right-footed cross to Fellaini at the back post.
It was evident from Mourinho's eagerness for his players to get crosses into the area as quickly as possible that he did not much rate Celta's capabilities in the air, and when Fellaini was isolated at the back post he did not miss.
Rashford's cross was evidently a consequence of something that Mourinho had impressed upon his players and the goal was well-executed.
They might have had more, with Henrikh Mkhitaryan sparking into life and swaying around two challenges in the midfield before releasing Jesse Lingard.
They let Celta back into the game at the end of the first half but it is a feature of this United team that they do not particularly seek out possession and as a result they invite pressure when others might seek to dominate.
They suffered for it in the second half when Vigo had a series of chances after the break, which a better team would have taken at least one.
Guidetti missed the best of those too, a cut-back from Pione Sisto after Hugo Mallo had crossed.
He was desperate to make an impact on this tie but his finishing got worse and worse.
Pogba and Ander Herrera tidied up in front of the back four and the former was outstanding at times at the difficult task of winkling out possession and putting himself between Vigo and the United goal.
Even so, the naturally defensive aspect meant that whatever Rashford wanted to do in attack he was obliged to do largely on his own.
The end was chaos.
First Guidetti missed with a header. Then after Facundo Roncaglia headed in a cross from the right, United faced the prospect of throwing away the tie.
It was Roncaglia who also saw red when Bailly was sent off for shoving him and in the end Guidetti could have won the game for Celta but it passed him by like so much else did on the night and United's season survived.