Alex Telles is set to miss the start of the season, with Manchester United boss Ole Gunnar Solskjaer saying he expects the Brazilian's ankle injury to rule him out for the whole of August.
The defender picked up the injury during pre-season training last week and Solskjaer had initially said the left-back would be "out for a few weeks".
A further update from the Norwegian on Tuesday revealed Telles is likely to be unavailable for the first three games of United's Premier League campaign, against Leeds at home on August 14, Southampton away eight days later and then Wolves away on August 29.
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Solskjaer told United's official website: "Unfortunately, it's worse news on Alex Telles than we hoped for.
"His ankle injury is a little bit more severe than we hoped and he'll be out for a little spell at least, the whole of August I would think."
Telles was signed from Porto last summer for £15.4m to provide competition for Luke Shaw at Old Trafford.
However, the England left-back responded well to Telles' arrival and had his best season in a United shirt after years of inconsistency, keeping the Brazil international to just nine Premier League appearances.
Roma have held talks to sign Telles from United this summer, according to Sky in Italy.
Now managed by former United boss Jose Mourinho, Roma are in the market for a left-sided defender after Leonardo Spinazzola picked up an injury while representing Italy at the European Championship.
Bruno expecting exciting season at Man Utd
Bruno Fernandes believes improving Manchester United will be even better this season as the playmaker looks to bring silverware to a club making impressive moves in the transfer market.
Solskjaer's side finished as Premier League runners-up last term and fell to an agonising penalty shootout defeat by Villarreal in the Europa League final in Poland.
United are preparing for a new season in a stronger-looking position, having last week completed the £73m acquisition of long-standing target Jadon Sancho from Borussia Dortmund.
The Old Trafford club have also had a £41m offer accepted for standout Real Madrid defender Raphael Varane.
Further moves may be dependent on sales but Fernandes is excited by the quality at United's disposal, positing on social media that he was "seeing good things coming in the new season".
"It could be in my personal life, the good season," he said with a laugh when that comment was put to him.
"No, obviously I think as always we have a chance to win whatever we want, or wherever we try to win because I think last season unluckily for us we don't get to win any trophies.
"We get to the final of Europa League but unluckily we don't win.
"But, still, with the transfers or without the transfers, Manchester United will always be a tough opponent, we will try to win every competition we are included [in].
"As I always said, for me, being at this level, at this club, we want to win. It's because of that I know we have the chance to win everything we are included [in].
"After, you can win or not, but we have the chance and we should and we will do our best to win something of course."