Potter said that Christian would be out for weeks with a knee injury.
The United States player was forced to leave the game in the first half after a challenge with John Stones.
The fans are fed up with the results.
After the FA Cup third round match on Sunday, Potter said that Pulisic is going to be out for a period of time.
"Christian opened up his knee in the game, so we're still analyzing it, but it is going to be weeks," Potter said.
Potter is facing a growing injury list at a team that has lost six of their last nine games. After being taken out of the game against City after five minutes, he didn't get to play in the cup tie.
"Raheem had an action, first minute of the game, he felt something in his leg, so we are analyzing it," Potter said.
Pierre-Emerick Aubameyang was unable to travel to Manchester because of a back injury, while the rest of the squad were also absent.