The Premier League champions are set to face their neighbours in the curtain-raiser for the 2011/12 season at Wembley, with tensions between the pair as high as ever following City's rise to the upper echelons of the English game in recent seasons.
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But Phelan insists the match is just another chance for the Old Trafford side to prepare themselves for the new Premier League campaign.
"It is no different. It is a tasty one of course because it is the two Manchester clubs coming up against each other," Phelan said.
"But we may try out a few new things. We have a week to prepare."
The last time the two sides met was in last season's FA Cup semi-final, also at Wembley, and Phelan believes United must put that 1-0 defeat behind them.
"The FA Cup semi-final was disappointing. But this is a new season. We will have a look at a few new players to see if they can handle it and take us into the league. That is what it is all about.
"Manchester United is all about challenges. You get them every day. Next Sunday will be no different."
"Manchester United always have to play well," Phelan added. "We always have to be in contention to win things. It will be no different next season. If anything it will be even harder.
"We worked very hard to achieve what we have in the past. Next season will be very difficult because there are a lot more threats now than there has ever been before."
Manchester United will kick off the defence of their Premier League title with a trip to West Bromwich Albion on August 14.
