Rooney believes Arsenal have been inspired by the talents of Robin van Persie and Aaron Ramsey.
Arsenal not mentally scarred - Wenger
Van Persie has scored 18 Premier League goals this season, equalling his best-ever total in a league campaign, while Wales skipper Ramsey has caught the eye with a series of confident performances in midfield.
"Van Persie is scoring a lot of goals, playing really well, and he'll be the biggest threat for Arsenal on Sunday," said Rooney. "He and Ramsey are certainly the two standing out for them this season."
Rooney scored a hat-trick in the 8-2 win in August, with his final goal coming from the penalty spot. His recent penalty record is patchy, with four misses from his last eight, but he insists that he will step up should United be awarded a spot-kick.
"Of course I'll still take the penalties," he said. "These things happen, sometimes you miss, it's not nice to miss but I'm not worried about it."
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