Derry banned talk of Championship Leeds' third-round trip to the Cambs Glass Stadium until after the January 2 win over Notts County.
And his desire to focus on League Two has paid dividends as Cambridge have six wins and a draw in their last seven games, while also beating Coventry 4-0 in the FA Cup second round.
"As players, as management, we've not been able to talk about it, because we've been very much concentrating on the league results," said Derry, who spent three years as a midfielder at Elland Road.
"We've been driving up that league and it enables us to go into Monday night's game full of confidence, which is something that really excites us all.
"We want to continue to do well in the league, but we want to cause a cup upset.
"We want to win, we want to beat Leeds United
It's a mighty task for us, but we want to come through in that fourth round."
Leeds were relegated from the top-flight in 2004 and Derry was part of the team which reached the Championship play-off final in 2006, but lost to Watford.
He still retains great affection for the club and praised the job Garry Monk is doing at Elland Road.
Derry added: "To pull on the mighty white shirt as often as I did and captain the club as well, to take us so very close to getting back to the Premier League when I was playing for them holds a lot of pride.
"To play for a big football club, to play for one of the magnitude of Leeds United was very much rewarding to me.
"It's a great time for Garry and his team
They've got unity up at Elland Road.
"The community is so buoyant when the football club goes well
The whole city comes to life.
"And they've done well
Garry's done remarkably well
He's a Premier League manager that in my opinion should never have got sacked by Swansea.
"He took his own stamp into Leeds United and he's reaping the rewards."
Leeds play in the Championship against Derby on Friday, with Monk upset at the "ridiculous" fixture schedule.
The former Swansea boss plans to rotate his squad and is wary of Cambridge.
Monk said: "You always have to look at the bigger fixture and I think it is ridiculous that we have to play on Monday and Friday.
"It is about getting the balance right, we want to win the game, but it is also about using the squad correctly.
"Cambridge are in really good form, they are doing really well in League Two, so we know it is going to be difficult.
"There is always a chance of an upset, but we are focused on putting as much determination, passion and desire, along with our best football on to the field like we do in every other game."
Source : PA