Skipper Chris Brunt and right-back Billy Jones have failed to recover from respective hamstring and knee injuries suffered during the first half of last weekend's 1-1 draw at Aston Villa.
The Baggies are already without first choice right-back Steven Reid (hamstring) and back-up keeper Boaz Myhill (hand).
Northern Ireland international Brunt had only just returned to the side after being laid low with other injury problems.
In addition, winger Jerome Thomas' return to training after various injury setbacks has been curtailed by illness.
But Baggies boss Steve Clarke has challenged the fit members of his squad to effectively fill the gaps.
He said: "We gave quite a positive injury bulletin mid-week but unfortunately this game has come too quickly for some people.
"Myhill, Reid, Jones and Brunt won't be fit. We are missing a few bodies.
"Hopefully it won't affect us at all because we've shown this year that we have a good squad. We've utilised the squad well.
"The players that have come in off the bench have always made a really positive contribution and we hope that will continue this weekend."
Regarding Thomas, Clarke added: "He started training this week but unfortunately the last two days he's been off ill.
"He's had a terrible time since I came here with one injury after another.
"All those have cleared up. Unfortunately he fell ill during the week and we are hopeful next week we can start right from the beginning and get some good work into Jerome."
Striker Peter Odemwingie is available to face QPR after serving a three-match suspension for his red card at Fulham.
But the form of four-goal Shane Long and on-loan Chelsea striker Romelu Lukaku means the Nigerian international may have to battle for his place.
Albion are bidding to achieve a fourth successive home win at the start of a season for the first time in the top flight since 1919.