The Catalans have been widely lauded for their slick tiki-taka passing, but Rooney believes it is Barca's ability to defend as a unit which has made them such a fearsome force.
"I think when you watch Barcelona a lot of people go on about their passing and the skills and how they keep the ball," Rooney said at a launch event for FIFA 12.
"But, for me, when they lose the ball, how quickly they all defend and try and win the ball back, that's the biggest asset they've got I think.
"They win it back so many times in the opponents' half and attack from there, so we've started trying to bring that into our game and thankfully that's started paying off for us."
United clearly do not have a great record against Barcelona, having lost two of the last three UEFA Champions League finals to Pep Guardiola's men.
Next month, Sir Alex Ferguson celebrates 25 years in charge at Old Trafford and with the legendary United manager at the helm Rooney is confident they can turn the tables on Barca.
Asked what three words summed up the boss, Rooney said: "Winner, desire and fearsome."
"It's unbelievable what he's done for the football club and the turnaround since I've been there is massive.
"From when he took over in '86 it's incredible what he's achieved at the club and the desire he has, still now, is frightening."
As for the Barclays Premier League trophy, Rooney does believe Manchester City and Chelsea will be their main rivals this season.
"They're obviously rivals and they'll be challenging for the league, there's no doubt about that," Rooney said.
"I think between them and Chelsea they'll be our two closest rivals and just behind them maybe Liverpool, Arsenal and Tottenham.
"But it's going to be a tough league and everyone will be going for that first place, so we need to make sure we stay on our toes."
Manchester United host Norwich on Saturday.