The Rams captain and former England skipper has had a huge impact since arriving at Pride Park in January, in both a playing and coaching capacity.
Thursday’s home tie against the Red Devils is a massive opportunity for Cocu’s side and the Dutchman reckons Rooney’s Old Trafford pedigree will be a major factor.
“Of course Wayne is very important, and maybe even more so in this game because he knows Manchester United like no-one else,” he said. “He knows the players, the level of performance, what is needed in those big games. So yes, it will be extremely important for us on Thursday.”
Cocu admits the amount of attention Rooney draws helps ease the pressure on some of his younger, inexperienced squad.
“I think it could be important for the rest of the team,” he said. “He’s used to the big games, he’s used to the attention.
“So maybe it will only have a positive influence on his performance, I think. But if you’re not used to playing these kind of games, it’s better that the attention goes to more senior players and you just focus on your task and your job in the team.”
Rooney – who has never scored or even won a point against United in six Premier League games before or after his 13-year stint there – will be utilised tactically by Cocu and his staff.
“We speak with Wayne before every game,” the Rams boss said. “He joins in with the technical staff in preparation for games, to analyse the opponent, to select the clips we want to study.
“I always ask his opinion not only for this game because he obviously knows the club very well, but I think this is the way we work. He is a player that’s the most important, and he wants to play, but he’s also very involved in the team tactics and how we approach the game.
“So yes we’ll use that for this game, and we won’t change that.”
Cocu is eager to take the pressure off his young side when Ole Gunnar Solskjaer’s team roll into town.
“I try not to say much to the players about the occasion,” he said. “I want to just let them enjoy the game and focus on playing football. Then it’s up to the senior players to lead the team and follow the game-plan and just let the young guys enjoy it.”