The match has taken on the status of a crucial relegation clash after Newcastle's awful run of form coincided with QPR's mini-resurgence under Harry Redknapp.
While the Magpies have lost six of their last seven games, winning only once, Rangers are unbeaten since their new manager took charge and ended a season-long winless run with a 2-1 triumph over Fulham last weekend.
There are still seven points separating the two teams, but with Newcastle scheduled to play both Manchester United and Arsenal away over Christmas, victory over QPR has become imperative for Alan Pardew's side.
Williamson told the Daily Mail: "We have had a lot of big games and QPR is right up there with the most important. The lads know that and we are solely focused on getting the win.
"It is a must-win for us and we go into every game with that mindset, but with Manchester United and Arsenal coming up, it is even more so."
After enjoying so much success last season and winning widespread praise for their performances, Williamson admits Newcastle's struggles this year have come as a shock.
They have won only four of their league 17 games so far - all at home - leaving their fans looking forward to European ties one minute, but fretting over a relegation battle the next.
Williamson added: "Last season, everyone was coming up and patting us on the back. Now they are asking us what has gone wrong.
"This is such a passionate city. They [the fans] deserve to see a few more better displays. We are all working hard to try to put things right and give the fans something to cheer."