The Ecuador winger will miss the rest of the campaign after suffering a sickening broken ankle against Rangers on Tuesday night.
Nightmare: Antonio Valencia is facing nine months out of the game
Valencia was carried off on a stretcher - aided with an oxygen mask to combat the horrific pain - after catching his studs in the Old Trafford turf.
Darren Fletcher, who was on field with Valencia when the accident happened on the hour mark, says Valencia will return even stronger after his long lay-off.
He said: It looked really bad. Hopefully the scans show it is not as bad as we fear. 'After arriving from Wigan he had a great first season and was looking to push on this year. That is why the injury is a real blow.
'He has only just got back from the injury he suffered at the end of last season too. He is a strong character and a good lad. He has real determination and works hard. He will be back I am sure. He will have a long future at Manchester United.'
Agony: Valencia receives oxygen moments after the horrific injury
Valencia will have an operation in hospital to reset his dislocated and fractured left ankle.
Ecuador national team doctor Patricio Maldonado has been kept informed about the injury and said: 'It is a double fracture to the tibia and fibula in his left ankle. He will be operated on.'
The Ecuadorians expect Valencia to be sidelined for at least five to six months, which would give him a chance of playing again before the end of the season and the Copa America next summer.
The weight-bearing tibia meets the more slender fibula at the ankle and both are often broken in serious ankle injuries.
Hector Bohorquez, another member of Ecuador's medical staff, said Valencia would need psychological as well as physical support. He added: 'This type injury has a huge impact on athletes who see how their bones have become detached. He must be continuously supported.'
United manager Sir Alex Ferguson has already admitted he does not expect Valencia to be available for the remainder of the season and likened the injury to that which Alan Smith suffered in similarly freakish circumstances against Liverpool in 2006. Smith has not been the same player since.
Ferguson said:'Ferguson said: 'It looks like a dislocation and fracture. That's a bad one. It will keep him out for a long time. He seemed to catch his toe in the turf and we knew straight away it was a bad one from the way the Rangers player started to wave.'
Aside from the injury itself and Valencia's recovery time, it leaves Ferguson with a problem so soon after the transfer window closed.
With games beginning to pile up, starting with Sunday's clash against Liverpool, United are left with only three orthodox wingers, one of whom is the largely untested Gabriel Obertan and another, Ryan Giggs, who cannot be expected to feature in every game just two months short of his 37th birthday.
Park Ji-sung, Javier Hernandez and even Fletcher himself are capable of operating in that area but are not natural wide-men, with so much now resting on Nani if United are to keep pace with Premier League title favourites Chelsea, having already fallen four points off the pace.
Pure pain: Valencia catches his studs in the Old Trafford pitch against Rangers
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