McDermott was dismissed with the newly-promoted club struggling in 19th place in the Premier League ahead of the visit to Old Trafford.
| READING LATEST
|40/1||Reading are 40/1 to beat Manchester United 1-0 with William Hill
"It's been a difficult week for everybody," he told reporters. "The players were on the floor at the start of the week.
"The owner [Anton Zingarevich] has asked me to take the team on Saturday. That's my only thought. That's the honest answer."
Dolan denied reports suggesting that Zingarevich would select the team for Saturday's match in the absence of a permanent boss.
"Obviously not," he said. "He's asked me to pick the team. He's talked to me about the team and trying to get a result - genuinely that is all he has said.
"I'm excited about going to Old Trafford. Really excited about that."
The Irishman confirmed that he had spoken to McDermott, who led Reading to the Championship title, since his sacking on Monday.
"Brian is a great friend of mine," he added. "I've spoken to him each day. He's a great man. All he has said is: 'Good luck, get a result'. All he wants is for Reading to get a result."