Juan Mata revealed in the week that he hopes to be back in action for Manchester United in the near future.
But Jose Mourinho has confirmed the Spain international will not be back until the "end of May", which makes him a huge doubt for the Europa League final, should United get there.
The United boss will also be without Phil Jones and Chris Smalling until "mid-May", meaning his centre-back options are limited until the end of the season.
Jose Mourinho provided updates on Chris Smalling, Phil Jones and Juan Mata
Juan Mata is unlikely to play again this season
Eric Bailly and Marcos Rojo have played United's last six matches in all competitions at the heart of the defence and will likely continue this Sunday against Chelsea (4pm).
With the race for Champions League football hotting up, Mourinho admits United may have to prioritise one of either the top four race or winning the Europa League.
"It is an amazing mentality by Eric and Marcos but they have to go to the limits," said Mourinho.
Manchester United team predicted to face Chelsea Fri, April 14, 2017
Click through the gallery for the predicted Manchester United team to face Chelsea
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Click through the gallery for the predicted Man United team to face Chelsea
"There is nothing I can do. There is no other chance. We don’t have other central defenders, they have to go.
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"If we arrive into a situation in the Premier League where mathematically the top-four is not possible, then it’s an easy decision: rest them and go with them in the Europa League if we’re still in.
"But at this moment we are in a position where we have two matches in hand. If we have win both matches we are in the top-four. We have to fight for every game."