Eduardo Vargas opened the scoring on the quarter-hour mark with a long-range drive, before Charlie Austin headed home and Bobby Zamora lofted a stunning lob past Boaz Myhill to give the R's a three-goal lead at the break.
Substitute Victor Anichebe's close-range header gave the Baggies a fighting chance, but that was soon extinguished as Youssuf Mulumbu was sent off for a foul on Joey Barton.
The QPR skipper went on to add a fourth in second-half injury time to help send his side to 18th in the league and just one point from safety, while West Brom stay 14th.
Here's how the action unfolded with Sports Mole's live text commentary.
Good afternoon folks, and welcome to Sports Mole's live text coverage of the Premier League clash between West Bromwich Albion and Queens Park Rangers at The Hawthorns this afternoon!
West Brom have certainly seen their form improve since replacing Alan Irvine with Tony Pulis as their manager earlier this year, having lost just twice in their last seven league outings. This has seen the Baggies climb to 14th in the table and while they're not quite safe yet, the outlook is promising.
The same cannot be said of QPR, however. They're second from bottom and have lost their last five league games in a row, and while four points from safety is not insurmountable, they will really need to get themselves into gear, and fast.
Two changes for the Baggies then as Chris Brunt returns from suspension and replaces Jonas Olsson in the starting XI, while Craig Dawson serves a one-match ban and is out, with Brown Ideye taking his place.
It's worth noting that Chris Ramsey hasn't been afraid to blood in youngsters this season; indeed, academy midfielder Frankie Sutherland has been named on the R's bench for the first time in the Premier League.
Both sides today changed their managers in the first few weeks of the calendar year in a bid to climb out of trouble, but it's safe to say that, on current evidence, they've gone in entirely different trajectories.
Since Pulis's arrival at the start of January, the club have kept six clean sheets in seven home games, and Saido Berahino has scored eight goals in those seven games.
By contrast, Ramsey has notched up just one win since taking the reins at Loftus Road at the start of February - QPR have taken fewer Premier League points in 2015 than any other side.
The reverse fixture in December was one of QPR's few bright sparks this season, as they came back from two goals down to win 3-2 at Loftus Road, courtesy of Charlie Austin's emphatic hat-trick sealed with just four minutes left in the game.
Interestingly, despite the struggles experienced by these two sides this season, it's worth remembering that two of the three highest-scoring English strikers this season play for them. Austin with his 15 league goals for the R's and West Brom's Saido Berahino with 12.
In fact it wasn't long ago since the media and fans were collectively singing their praises as England's next great hopes. That said, they've had their thunder stolen somewhat by one Mr. Harry Kane with his frankly preposterous 19 goals, despite taking a while to break into the Spurs team.
I'm expecting there to be quite a few goals this afternoon - fifteen of Saido Berahino's 18 goals for West Brom this season have come at The Hawthorns, while Joleon Lescott has given away three penalties in the league this season, more than any other player.
QPR will also play their part, because it's do or die for them now. Ramsey told the media this week that his side is targeting "four to six points" in their next two games, so they will be going for it - and with Austin in their line-up, they're more than capable of breaching the opposition backline.
PREDICTION: Well, we're nearing kickoff, so it's time for me to have a go at predicting the result. I reckon it'll be a 2-2 draw, with Berahino and Austin to get at least one goal each for their respective sides.
Vargas and Austin kick off, and their first action is to play it back towards defence where the ball is punted straight to Boaz Myhill in the West Brom goal.
CHANCE! Ideye musters up the first chance of the game as he latches onto Brunt's cross to send a header towards goal, but Green collects it harmlessly. At the other end, QPR race forward but Zamora is ruled offside.
CHANCE! Lively start here from both sides as QPR get a free kick in a promising position courtesy of Gardner's tackle on Austin. Phillips tries his luck with a curling effort but it flies straight into Myhill's grasp.
Vargas gives away a free kick for West Brom after bringing down Berahino which is easily cleared out of the box. Moments later Morrison has a crack from distance, but the effort flies harmlessly above the bar.
Pretty even so far, with West Brom just about edging things, but after the high-tempo start and chances early on, it's now settling in midfield as both sides tighten up.
Wow! Now that is a beauty! Austin's the architect as he nods on a long ball forward, with Vargas collecting and smashing a rocket of a shot from 20 yards past Myhill and into the bottom corner of the goal! Just the tonic for the visitors.
It's advantage QPR and they now have the momentum, knocking the ball about quite confidently. Can they build on this, both in the game and in the season?
CHANCE! West Brom nearly get back into this as Ideye is in the perfect place to work a Fletcher cross, the ball bouncing off his leg and nearly trickling into the near post! QPR will be breathing a sign of relief there.
Phillips is determined to double his side's lead as he marauds forward, cutting onto his left foot and dragging wide of the right upright from outside the area.
BOOKING: Gardner is brought down by Caulker on the edge of the area and the Baggies have a free kick, with the defender earning himself a yellow for his troubles.
The game is being played at high-tempo, but there is now a break in play as Vargas is down and in some pain. He appears to have twisted his knee trying to kick the ball while it was in the air.
SUBSTITUTION: Vargas gets up to his feet and appears able to carry on, but with considerable discomfort. He's taken off, as Niko Kranjcar comes on in his place.
No clear favourite here as both sides continue to push forward tentatively. West Brom apply some pressure but Gardner's final cross is too deep and trickles out for a goal kick.
Well, who could have predicted this? The visitors surge into a two-goal lead here at the Hawthorns, and the prolific Austin notches up another goal - his fourth against West Brom in the league this season!
A corner is played towards the near post, where Kranjcar flicks it on across goal, and Austin is at hand to launch himself into a diving header to send the ball into the net and double QPR's lead!
Brunt looks for an immediate response when he lets rip from outside the area, and the ball takes a wicked deflection as it heads towards goal, but Green has it covered well nonetheless.
OH MY DAYS THAT IS SENSATIONAL!! That, my friends, is the kind of the goal that leaves you pulling a stupid face as you go "ooooooohhh". Zamora gets on the end of the ball just inside the box as Lescott closes in, so the striker decides to just give it a go and strikes a lob with the outside of his foot that sails over Myhill and clips the inside of the post before going in!
Well. Who could have predicted this kind of scoreline at half time? Very few people had given QPR any chance of doing well in this game, given how poorly they travel and considering West Brom's good form at the minute. But it is in fact 3-0 to the Premier League's second-from-bottom side.
Tony Pulis will be having some very stern words with his players. They've not really turned up this afternoon, even though two of the QPR goals were pretty special. I mean, that Zamora one has to be in the top five goals this season.
The Baggies still have 45 minutes to turn things around but unless they can get themselves a quick goal after the restart to boost morale and deflate the opposition, they're going to struggle to get anything from this game.
The team talk in the QPR dressing room will be interesting too, because as happy as they will be with their clinical and emphatic performance in the first 45 minutes, they must not get complacent - they have to really focus once they get back into the pitch.
If QPR can hold on for victory it will really blow open the bottom seven. Ramsey's men will move within a point of Sunderland and safety if they hang on, with Albion being dragged back into the mire ahead of a tricky set of fixtures coming up for them.
West Brom have begun this half with intent as the ball is played short to Ideye from the left. He then hits a swift shot that gets deflected out of the box for a corner.
PENALTY SHOUT: Anichebe claims that he was held by Onuoha in the box as the West Brom striker tried to latch onto a Brunt cross. It would have been a very soft penalty but he did have a case - nothing given though.
PENALTY SHOUT: The ball appears to hit Brunt's outstretched hand in the West Brom box, but the referee refuses to give QPR a penalty. The visiting players are not impressed.
Just what Pulis would have wanted as his charges pull a goal back at a decent time in this game. Berahino shrugged off a tackle from Isla down the left flank before slicing a nice cross into the box, where the lively Anichebe made no mistake from close range, nodding into the corner of the net. Game on!
QPR could have been four goals up just a minute earlier had that penalty been awarded, which would have killed the game off completely, but now their clean sheet has been breached and they will have to ensure that this solitary West Brom goal doesn't turn into something much worse.
CHANCES! It's end to end stuff here as Brunt sends a cross that Green has to dive to punch out of the box, before Kranjcar fires a weak effort at the other end right at Myhill.
CHANCE! West Brom have tailed off a bit after their goal just before the hour, but they come back strongly as Fletcher takes a shot that Berahino nearly bundles into the net with a clever flick, but it goes just wide of the target.
CHANCES! How many chances do the Baggies need?! A multitude of missed efforts from the hosts here as Berahino heads into the arms of Green from point-blank range, we're talking across the face of goal! And moments later a cross from Brunt is met by an Ideye diving header which crashes narrowly wide!
RED CARD! Mulumbu is given his marching orders after raising his arm and clattering into Barton as the midfielder rose to head the ball. Is that it now for West Brom?
Anichebe wins his side a free kick 12 yards outside the QPR box after being fouled by Henry, but the set piece is played wide and crossed in, and the visitors clear with ease. Another chance goes begging for the hosts, who have laid siege to Ramsey's charges but have little to show for it.
Two more free kicks conceded by QPR not far from their own box in a short space of time. Quite desperate defending but they really need to be more disciplined, because it they concede a goal this late, you never know what that will do to the players' minds.
What a sensational result here at The Hawthorns as Queens Park Rangers secure only their second away win in the Premier League this season in emphatic style, thumping West Bromwich Albion 4-1. Three unanswered goals by half time, including a sensational strike from Bobby Zamora, were followed up by a Victor Anichebe strike jut before the hour that threatened a revival, but the visitors saw the game out and added a fourth in second-half injury time through Joey Barton.
And as a result the lower end of the Premier League table has been blown wide open - QPR are now just one point from safety and three points behind Hull City, who are 15th. It's worth adding that Leicester City also won today, a 2-1 victory against West Ham United, so they're just four points from safety now as well! This will go right down to the wire!
My time on this live commentary has come to an end but don't go anywhere, because Sports Mole will bring you match analysis, player ratings and all the reaction from this and every other Premier League game today! Until next time, bye bye!
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