The Black Cats ended a three-game losing streak by coming back from two goals down to earn a draw against Fulham at the Stadium of Light last weekend.
And, though the Rs earned a morale-boosting victory over Southampton away from home last time out, Fletcher is certain Sunderland can come out on top.
“They’ll have a lot of confidence going into the game after the win last weekend but we have trained hard all week so we also have that confidence going into the match," he told the club's official website.
"Loftus Road is a tight ground and the fans are close to the pitch.”
The Scot went on to hail the recent form of his Sunderland attacking cohorts Danny Graham and Stephane Sessegnon.
“It’s been good to have Danny up front with me and have a partner - we have worked well in training too. Sess has been out wide in recent weeks and he is class," he added.
"He can play anywhere on the pitch and he has shown his quality over the past few weeks and got some goals for the team too.”
The £14 million man, who has scored 10 goals in 28 appearances since his summer move from Wolves, also had kind words for the Mackems' away support.
“We always take an amazing travelling support. We usually sell out the away end and that is massive for us. It makes a difference so hopefully we can send them home happy," he said.