Sir Alex Ferguson's side romped to a remarkable 8-2 win over Arsenal back in August, but Rooney knows the Gunners are much-improved since that humiliation and the United striker believes van Persie has been the key to their revival.
Van Persie has scored 20 times since the Old Trafford demolition and the Dutch forward has been almost unplayable at times.
If Arsenal avenge their Manchester mauling and dent United's bid to move level on points with leaders Manchester City, it is likely van Persie will have given another masterclass.
"Van Persie has scored a lot of goals and is playing really well," Rooney said.
"He will be the biggest threat for Arsenal on Sunday. Van Persie and (Aaron) Ramsey are certainly the two who have stood out for them this season."
With Rooney, who bagged a hat-trick against Arsenal in August, back in form after a barren run, Sunday's game promises to be a shoot-out between two of the best strikers of their generation.
The duo have 39 goals between them this season, but Rooney would gladly go without a goal as long as United leave with all three points.
"It is not about me and Van Persie," he said. "It is about us against Arsenal. That is what we will be focusing on."
After inflicting Arsenal's biggest defeat for 114 years, Michael Carrick is well aware the Gunners will be desperate for revenge and the United midfielder has warned his team-mates to expect a backlash.
"Maybe they will be thinking of revenge," Carrick said. "They didn't start the season too well but they are still up there.
"Arsenal against Manchester United is always a massive game. They will want to win and so will we."
With United playing a few hours before City host Tottenham, Ferguson's men have an opportunity to put serious pressure on the leaders.
They could be facing Arsenal at the right time as Arsene Wenger is without Mikel Arteta, Jack Wilshere, Andre Santos and Bacary Sagna, while Thierry Henry faces a late fitness test on a calf problem and Thomas Vermaelen is a severe doubt with the same injury.
In contrast, Ferguson's options have been boosted by the return from injury of England defenders Phil Jones and Chris Smalling.
While United need a victory to aid their title defence, Wenger would happily settle for finishing in the top four after his side made their worst start to a season for 58 years.
They go into Sunday's game in fifth place -- four points behind fourth placed Chelsea -- following successive defeats against Fulham and Swansea.
And Wenger claims the prospect of missing out on Champions League should be all the motivation Arsenal need to avenge that Old Trafford embarrassment.
"You want to play big games, and this is a big game that comes at a moment when we want to convince people that we are capable of coming back into the top four. There is no better opportunity than Man Utd to show that," he said.
"We are really frustrated because we made the minimum of our last two games, we were twice leading and in the end we lost them both.
"We were on a very strong run before that, and we lost that run in a way that is difficult to accept because everything went against us in the two games - but we have to accept that and win our game on Sunday."
With Tottenham well set in third place, Wenger concedes a defeat would be a major blow to their top four hopes, but he retains belief in his injury-hit squad.
"If you imagine a catastrophe, you can always make life difficult. You can go the other side, they (Tottenham) could lose, we can win," he said.
"That is why we love the league. It is just important that we keep our belief in our game, in our players, and that we go into the game with that belief."