McTominay had to be substituted during Thursday's 3-0 win over Partizan Belgrade, while Maguire also picked up a knock.
"I think Harry will be okay. He finished the game anyway," Solskjaer told MUTV . "Scott is more of a concern, so let's see how he recovers in the next few days.
"He said he was going to be okay out on the pitch and he said 'I'll be fine'. He's tough, but he had to come off.
"I hope he'll recover for Sunday, but I don't know. Inside of his ankle. I think he went over on his ankle."