Former Forest star Clough said after the game: "My only disappointment when the draw was made is that we weren't away.
"It would have been great for the lads to experience Old Trafford and I'm thrilled for their hard work that they can have it now.
"Manchester United in a replay is absolutely superb for everybody.
"The first half was pretty even but in the second half we were under the cosh.
"I didn't fear the worst really but if Manchester United hit top form I knew they could put three or four past us.
"In the second half they got pretty close to it and seeing Wayne Rooney and Ronaldo coming off bench does get you worried."