The Red Devils head into the match in West London top of the Premier League table, while hosting QPR sit bottom.
However, Parker, who spent five years with United up until 1996, believes that the size of the pitch at Loftus Road will act as a leveller.
"It's very tough at QPR as it's a small ground and it helps them," the 48-year-old told Man United's official website. "I tell you why they keep so many clean sheets there - it's because if a team's great strength is out wide then it kills them.
"It's why wingers have always struggled at QPR. The only player with any width who did well in my time there was Andy Sinton but that's because he had other things about him rather than staying on the touchline. It's a very narrow pitch. It's as simple as that and it's very easy to defend there."
Having begun his career with Fulham, Parker moved to QPR before joining United.