Nemanja Vidic hopes Rio Ferdinand will shake off a hamstring complaint in time to face Arsenal.
The England captain was forced off during the second half of United's 1-1 UEFA Champions League draw with Valencia on Tuesday.
Ferdinand was substituted as soon as it became apparent that he had a problem and it is hoped that swift action will benefit the Red Devils.
The 31-year-old has already revealed that he expects to recover in time for the club's next outing, and Vidic hopes that proves to be the case.
The Serbian knows how important it will be to have his defensive ally alongside him when Arsenal arrive at Old Trafford on Monday, with the Premier League's top two set to lock horns for the first time this season.
"Fingers crossed he will be okay," said Vidic.
"Against Arsenal we need to have experienced players on the pitch, especially Rio. I hope he will be fine and be ready because that is a very important game."
On the game itself, Vidic added: "Everyone looks forward to the big games and this is one of the biggest. In fact I would say it is the biggest game in this part of the season.
"At the moment Arsenal are playing good football and are top of the league. It would be nice if we could win the game and go above them.
"We are all aware it is a long season. You can already see how many teams are dropping points.
"It is too early to start talking about winning this one game giving us an advantage. But it would be nice to do it."
Meanwhile, Vidic has expressed his disappointment at missing out on a European clean sheet record in midweek, with Valencia's effort ending their hopes of securing a sixth consecutive shut-out, but admits he is pleased to have helped the Red Devils book their place in the last 16 as group winners.
"We wanted to break the record," he said. "That is a normal thing when you have kept five clean sheets.
"But the most important thing is that we finished where we wanted; first in the group.
"Hopefully now we will avoid some of the big teams, which helps us in the competition overall."