Reading travel to Old Trafford for tonight's televised fifth-round tie hoping to ambush United's attempt to repeat their treble success of 1999.
A 12-point lead at the summit of the Premier League points to their coronation as domestic champions after seeing the crown snatched from their fingertips by Manchester City in the dying moments of last season's title race.
McDermott believes the pain felt on the final day of last term has inspired United's position of dominance - and it is an experience to which he can relate.
"To move on the way they did from last season, to take that on to the pitch and that hurt, tells you the power of the people there," he said.
"The hurt that day would have given them a tough summer, but you have two ways of going - you either go under as a club or get stronger. United have got stronger.
"We can relate to that in a small way because we had the play-off final (Reading lost 4-2 to Swansea in 2011). We got stronger from our play-off final.
"No-one could have said that to me that night, because it was a really devastating blow. But you get up and move on and that's what they have done."
A hallmark of every side fielded by Ferguson is their unwillingness to concede defeat and McDermott insists Reading have sought to adopt that trait - with some success.
"That attitude comes from the manager and the ingredients he puts into the mix," he said.
"Sir Alex has an incredible will to win and you can see that from the way he is on the touchline.
"Whatever he puts into the game, they never feel like they are beaten. We're trying to get that too.
"Luckily we have had that over the last few years. We've kept going in the last few games particular."
McDermott is an admirer of United veteran Ryan Giggs and believes the former Wales winger has managerial potential.
"I met him recently at Burton. He was doing his pro license and he has got all the ingredients to be a top manager," he said.
"He is humble and quiet. I asked him how many medals he had won. He was very blase and just said 12.
"I asked what he did with them all and he said they were in museums. He was a really humble and polite man. I was really impressed, he came up to me and shook my hand."