Only 26 days after their last visit to Old Trafford, the Royals face Sir Alex Ferguson's side in the Premier League without a permanent manager, but Pearce says their remaining games are all cup finals, and that an upset could happen only a week after losing to relegation rivals Aston Villa.
"It's nine games left now and nine cup finals," he told The Reading Chronicle.
|18/1||The Royals are 18/1 with Bet365 to beat Manchester United by any score on Saturday
"They're not easy games but you never know in football. We can regroup this week and get ourselves together. If we go there and put on a proper team performance you never know what might happen.
"We're obviously very disappointed with the Villa result and the dressing room was very down, but we will never lose belief.
"We must pick ourselves up now, it's the only thing we can do. Everyone has written us off, they had done so before the season even started. We've got to stick together now, it's massively important."
Pearce bemoaned the treatment his side have got from referees this season, after seeing a penalty claim denied and a goal ruled offside against Villa, but says they have to make sure the referees are no longer the talking point.
"The offisde was a big decision but we have to eliminate talking about referees every week," he added.
"It seems to be happening quite a lot this season so we need to eliminate that and try to do as well as we can during games.
"We put up a good fight and I thought we played well in the second half. But we will move on and look to Manchester United this Saturday."