Pogba injured his thigh in a training session with France this week and the initial prognosis was that he could miss six to eight weeks.
This will be a big blow for Ole Gunnar Solskjaer and mean that he would be absent for 10 Premier League games and two Champions League matches.
It would also mean that the 28-year-old would be out for the rest of 2021, should he be on the upper end of the estimate or longer.
There has been uncertainty surrounding his future and it could well mean that Pogba has played his last game for the club.
The France World Cup winner is out of contract at the end of the season and Man United want clarity on the situation by Christmas.
Previously reports have said that the club do not want contract negotiations dragging out to the second half of the season, especially if it may detract from what is happening on the pitch.
Fresh claims in the Daily Star say the Red Devils are open to selling Pogba in January so they can cash in on him before he leaves for nothing.
He re-joined United back in 2016 in an £89.3million deal from Juventus, but has not fulfilled his potential at Old Trafford.
His form has been up and down and often looks a much better player when featuring for his country.
Real Madrid, Juventus and Paris Saint-Germain are all said to be keen on signing the midfielder.