The R's were 3-0 victors over Ipswich Town at Portman Road. Jamie Mackie scored two, with Heidur Helguson converting a penalty to ensure a fifth win from six games for Neil Warnock's side.
They now have breathing space at the top thanks to Cardiff City losing 2-1 at Leicester.
Lee Naylor had put the Bluebirds ahead at half-time, but two goals from Andy King secured the win for the Foxes.
Milllwall are third, five points behind QPR, after a goalless draw at home to Reading.
A hat-trick from James Coppinger saw Doncaster Rovers defeat Norwich City 3-1, moving them up to fourth.
A hat-trick from James Vaughan helped Crystal Palace to a 4-1 win over Portsmouth, who are already three points adrift of safety and without a win to their name.
Jimmy Bullard's return helped inspire Hull City to a 2-0 home victory over Derby County, with Daniel Ayala and Robert Koren scoring the goals.
Leeds United were hammered 5-2 in the South Yorkshire derby at Barnsley.
Nottingham Forest got their first win of the season thanks to two late goals from Lewis McGugan securing a 2-1 success at Preston.
A late goal from Tarmo Kink gave Middlesbrough a 2-1 home win over Burnley.
Swansea City were 2-1 victors at home to Coventry, despite a late push from the Sky Blues. Goals from Marvin Sordell and Danny Graham gave Watford a 2-0 win at Bristol City.