Pogba has missed four of the last seven United games with an ongoing ankle complaint and has failed to recover in time for Sunday's game.
De Gea will be missing too after an injury picked up for Spain on Tuesday night.
The goalkeeper tweaked something in his groin when clearing the ball and was immediately taken off.
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After the game, Spain manager Roberto Moreno revealed that De Gea felt the injury in the first half and aggravated it midway through the second 45 minutes.
"He had pain in the abductor muscle but he received treatment at halftime and wanted to keep playing," Moreno said, per ESPN. "He gave us his word, but in the end he couldn't continue."
Their task of beating the league leaders was already a tough one. But it's just got much, much harder.
Fortunately for United, they do have a capable replacement for De Gea.
Sergio Romero is Argentina's first-choice goalkeeper and is arguably the best second-choice goalkeeper in the Premier League.
Replacing Pogba, on the other hand, will be a trickier task.
Brazilian midfielder Fred has flattered to deceive since joining from Shakhtar last year but may be given his chance to shine against Liverpool.
There is some good news for Man United, at least.
Aaron Wan-Bissaka and Victor Lindelof are both expected to be available after recovering from injuries.
And Anthony Martial is also expected to return in what is a huge boost to United.
The French striker started the season in good form as he scored twice and recorded an assist in United's opening three games.
Ole Gunnar Solskjaer's side have looked poor in attack since his injury but Martial's return could change their fortunes in front of goal.News Now - Sport News