Sir Alex's side are looking to extend the lead at the summit to 15 points ahead of Manchester City's encounter with Chelsea on Sunday but will be fully aware of the defensive organisation of Harry Redknapp's Rangers. The Hoops have kept clean sheets against Chelsea, Tottenham and City and are unbeaten in their last four home matches.
Parker, who moved north from the capital in 1991, believes things may be awkward for United's wide players – the likes of Nani, Antonio Valencia and Ashley Young – if they are selected in the starting line-up.
"It’s very tough at QPR as it’s a small ground and it helps them," the 48-year-old told ManUtd.com. "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."
Although the West Londoners are currently bottom of the table, Parker is in little doubt that a team battling to fend off relegation will ensure an uncomfortable afternoon for United.
"QPR need a goalscorer as they haven’t got anyone to score goals," he opined. "Even Loic Remy has not scored goals regularly in France of late.