Jose Mourinho is sweating over the fitness of Nemanja Matic ahead of Saturday's showdown at the Emirates.
The Manchester United star limped out of the midweek win over Watford, but Mourinho will give the Serb the chance to prove himself for the crunch Arsenal clash.
"Matic is a doubt," Mourinho said.
"I hope he can but I cannot guarantee he is selected to go, let's see the feeling before the match, let's see the warm up, I hope he can, I want to, he wants to, but I cannot guarantee, and Fellaini is not travelling with the team."
Phil Jones, Eric Bailly and Marouane Fellaini remain sidelined.
Meanwhile, Mourinho has insisted United's clash with Arsenal is not a must-win game.
United trail Premier League leaders and local rivals Manchester City by eight points, ahead of what could be a title race-defining derby at Old Trafford a week on Sunday.
But Mourinho compared the battle between City and United to the rivalry between Bjorn Borg and John McEnroe after watching a film of their tennis rivalry on Thursday.
"I play a game at a time," said Mourinho. "I play a game at a time and is the way to do it, is the way to do it.
"Yesterday I was watching an interesting movie, Borg vs McEnroe, and Borg's coach was telling him that all the time - 'one point at a time, think about just one point'.
"I tell my players to just think about the game. It's just the game, it's Arsenal, we don't think about how many points we are behind, it's just Arsenal.
"It's difficult enough for us to be focused on other things, so just focus on this."
Asked if United were cast in the role of McEnroe and City Borg, Mourinho said: "No. I love tennis, but I don't play tennis."