Barcelona playmaker Andres Iniesta says Wayne Rooney epitomises Manchester United's sublime work ethic.
Although Rooney may not have scored the number of goals Barca's forward line have plundered this season, Iniesta believes he plays a key role.
Iniesta, who scored Barca's priceless leveller in their 1-1 draw at Chelsea, says Rooney's versatility and commitment makes him an invaluable member of Sir Alex Ferguson's squad.
The 25-year-old knows the UEFA Champions League final between the sides in Rome on Wednesday will be a tight affair and that keeping mistakes down to a minimum could be the key to success.
"What I value most about the way they play is how hard players like Rooney work," explained Iniesta.
"He was filling in at left-back against us last year in the semi-final.
"Finals are not usually very tactical. We can plan a million things before the game but in the second minute they can strike and all the plans go out the window.
"We cannot commit any mistakes because they have so much firepower up front."
Meanwhile, former Red Devils defender Gerard Pique believes that on his day Manchester United striker Wayne Rooney is unstoppable.
The former Red Devils stopper knows the England international well from his time at Old Trafford before his Camp Nou switch last summer.
"When he is focused he is simply unstoppable," explained Pique.
"I have never seen a player as powerful as Rooney - the way he goes past people, the intensity of his play, the runs he makes from the first minute to last and the shot that he has. World class.
"Perhaps he does not get the credit he deserves because he should score more goals, but he offers so much."