Heading into the encounter at Loftus Road, Redknapp's side are bottom of the Premier League table, while visiting United are 12 points clear at the summit.
However, Redknapp believes that some of the results his side have achieved this season show that any outcome possible.
"You can't predict results. We're playing Chelsea away on the back of being smashed to pieces by Liverpool. What's the score going to be you might ask? 3-0, and 4-0 to them? I was surprised as you were," he told the Fulham Chronicle.
"We then play Tottenham at home who've beaten everybody away and have scored in all away games and they don't score against us.
"Against Man City, who are champions, we get another great point and then another at West Ham, which is a hard place to go. So we're just as capable of getting something against Man U as anyone else."
QPR have not beaten United at home since May 1989.