Back-to-back clean sheets and a return of four points from the last two games have seen West Brom climb to 14th in the top flight.
But QPR, who occupy the final relegation spot, are just three points behind and are on an impressive run of form at home, having claimed 10 points from the last 12 available at Loftus Road.
Irvine recognises the significance of the clash against another team looking to pull away from the bottom three, but is confident that his side's efforts on the training ground will prove valuable.
"It's a big game - big game for them, big game for us," he told the club's official website. "It would be great for us to follow up two positive results with another good one there. But their home record of late is very, very good.
"[It has been] good to get a couple of clean sheets. It's been on the back of work that's been done in the past in training.
"There have been some very, very good defensive performances and that starts from the front. But it also it comes at a time when we've been doing a lot of work on getting forward."
The visitors will have to contend with a QPR side boosted by the return of eight-goal top scorer Charlie Austin from suspension.
Austin netted against former club Burnley in the previous home game before picking up a second booking that ruled the striker out of Monday's 3-1 loss at Everton.
West Brom's leading goal threat has been in poor form of late, though, with Saido Berahino having failed to find the net in his last eight appearances in all competitions.
Irvine has used Berahino as a substitute in the past two matches, indicating his belief that the England Under-21 international needed a break from being West Brom's attacking focal point.
With Brown Ideye having produced a lively display in the 1-0 triumph over 10-man Aston Villa last Saturday, Berahino has a battle on his hands to earn a recall.
West Brom will certainly sense an opportunity to get at QPR, despite the home side's impressive Loftus Road record, with Harry Redknapp's men having shipped a league-high 30 goals this season.
All three of QPR's clean sheets have come on home soil, however, in wins over Sunderland, Villa and Burnley.
With Austin back in the frame, QPR have no new injury concerns to contend with, while West Brom could soon welcome back Victor Anichebe (groin) and Chris Brunt (hamstring).
West Brom did the double over QPR the last time they were both in the Premier League, during the 2012-13 season.
