Manchester United boss Ole Gunnar Solskjaer is hopeful Paul Pogba, Victor Lindelof and Luke Shaw will be fit to face Liverpool on Sunday but admits the trio could miss Tuesday's game at Burnley.
United beat Watford 1-0 at Old Trafford in the FA Cup third round on Saturday but Pogba, Lindelof and Shaw did not feature in the matchday squad.
Solskjaer confirmed after the match the trio were absent through injury and has now cast doubt on their fitness ahead of a crucial week for his side in the Premier League.
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United will go top of the table if they get a positive result against Burnley on Tuesday, which would add extra fuel to Sunday's trip to current leaders and bitter rivals Liverpool at Anfield - both games live on Sky Sports.
"I hope so, I hope all of them for Liverpool, definitely," Solskjaer said. "I'm not sure if they'll make the Burnley one.
"But light training (on Sunday) then we'll have to see on Monday."
There are also concerns over Eric Bailly, who was forced off just before half-time against Watford with a head injury. He will need to be assessed before the match at Turf Moor.
Ole rejects title talk: 'We're not even halfway'
United have won eight of their past 10 Premier League games and are only behind Liverpool on goal difference.
Their rich vein of form has prompted talk of a first serious title challenge since Sir Alex Ferguson retired, but Solskjaer again downplayed the importance of his side's shot at reaching the summit.
"We're not even halfway through the season yet," he said.
"Every game in the Premier League is a challenge, is a test. Every game gives you a different test.
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"Watford, they gave us a test. Burnley is one test, Liverpool is another, then you go to Fulham, which is a different test again.
"No one will remember how the league table looked like on the 12th of January in 2021."
Solskjaer has understandably resisted talk of a title challenge when it has been brought up, but the United boss appreciates building fan excitement ahead of a big week.
"I think it's great that our fans are excited and that they're happy with where we are at and that we have this little sense of excitement," the Norwegian added.
"But then we're not even halfway through the season so of course every game against Burnley, or every game against Liverpool matters a lot anyway.
"For me, all my eyes are on Tuesday and then let's see where we're at after that one."
Watch Burnley vs Manchester United live on Sky Sports Football from 8pm on Tuesday; kick-off 8.15pm. Manchester United then travel to Liverpool on Super Sunday, live on Sky Sports Premier League from 4pm; kick-off 4.30pm.