The matches at Loftus Road and Elland Road represent the headline fixtures on another busy Saturday that will see second-placed Burnley host out-of-form Blackpool.
QPR secured a 2-0 win at Blackpool last week, courtesy of goals from Matt Phillips and Charlie Austin.
That result - coupled with Burnley's 1-1 draw at third-placed Leicester - saw Harry Redknapp's men take over at the top of the table and winger Phillips is eager for the club's good run to continue.
"This is a massive month. If we can get the right results over the Christmas period then it will stand us in good stead for the remainder of the season," Phillips told QPR's official website.
"You don't get easy matches in the Championship so Leicester on Saturday will be another tough test.
"However, with the belief we have in the dressing room we go into it full of confidence."
Leicester are without a win in three league matches and visit a ground that QPR have claimed 26 points at from 10 games this season.
New Barnsley boss Danny Wilson began his managerial career at the club 19 years ago only to leave in 1998 following their relegation from the top flight.
After managing six clubs in the Football League, he will begin his second stint at Barnsley, the Championship's bottom club, with a Yorkshire derby against a Leeds United side who have won out of six at home and sit sixth.
Leeds also have Ross McCormack, who is the league's top scorer with 16, having found the net 11 times in his last seven matches.
Watford also start a new era, with head coach Giuseppe Sannino's first match coming at Ipswich Town.
Watford have not won in nine, and lost their last five home matches, but Italian Sannino - appointed on Wednesday to replace Gianfranco Zola, who resigned - brings a wealth of European experience and will be keen to immediately reverse their fortunes.
Having claimed just one win in eight, Burnley will seek a much-needed three points against a Blackpool side boasting only three wins from their last 14 games.
High-flying Derby County have risen to fourth with a run of six wins in a row and host struggling Doncaster Rovers.
Two other teams involved in the play-off hunt - Reading and Nottingham Forest - take on Wigan Athletic and Birmingham City respectively.
At the other end of the table, second-from-bottom Yeovil Town will hope to extend a four-match unbeaten streak and climb out of the bottom three with a positive result at home to Blackburn Rovers.
Sheffield Wednesday have won two of their last three and host Bournemouth while Charlton Athletic and Middlesbrough hit the road to face Bolton Wanderers and Millwall.
And in-form Brighton and Hove Albion, who have lost just once since October 5, host Huddersfield Town.