Kevin Phillips bagged a brace, as free-scoring West Bromwich Albion produced a five-star show to extinguish the R's unbeaten away run.
Rangers were second best in every department at The Hawthorns, on a day when the Baggies ran riot in front of the live Sky Sports cameras.
The R's trailed 3-1 at the end of an enthralling first period.
Albion opened the scoring in the 18th minute courtesy of Phillips, before he turned provider for Ishmael Miller, who sprinted beyond a static Rangers rearguard to make it two 60 seconds later.
The R's briefly rallied and when Gareth Ainsworth made it 2-1 when he smashed the ball home from close range in the 24th minute, the visitors sensed a revival.
But Albion restored their two-goal buffer just before the break, as Phillips notched a sublime goal, curling the ball past Lee Camp from the edge of the penalty box.
The rampant hosts made certain of the victory early in the second half, when Robert Koren smashed an unstoppable strike past Camp, before Jonathan Greening sent a fearsome 25-yard volley into the far corner to make it five.
With Danny Nardiello (hamstring) and Sampsa Timoska (illness) both ruled out, John Gregory handed starts to Ben Sahar and Zesh Rehman at The Hawthorns.
Ainsworth and Adam Bolder both overcame ankle and knee injuries respectively to play, while Stefan Moore replaced the suspended Mikele Leigertwood.
Veteran striker Phillips led the Baggies front-line, while at the other end of the pitch, Dean Kiely - who saved a Paul Furlong spot-kick the last time the two sides met - lined up in goal.
Albion made much of the early running, with Miller at the heart of their positive start.
In the eighth minute, the Manchester City loanee sent an enticing cross into the near post, which Damion Stewart did well to clear, under pressure from Phillips.
Miller was at it again a minute later, only to see his scuffed effort deflected wide by the outstretched boot of the Jamaican international defender.
It was all West Brom and when Phillips met Jonathan Greening's corner kick in the ninth minute, Rowlands was in the right place at the right time to clear his half-volley off the line, albeit by the aid of the post.
Miller was proving a constant threat and when he skipped past Rehman with ease in the 17th minute, Phillips was left with the easiest of tap-ins from two yards, for his fifth goal of the campaign.
Seconds later Miller made it two, when he arrived onto Phillips' precise through ball before baring down on goal and slotting the ball underneath the exposed Camp from 15-yards.
Undeterred, the R's got themselves back into the game in the 24th minute.
Rowlands flighted in an inviting free-kick to the back post and Dexter Blackstock headed across goal for Ainsworth to tap home from little more than a yard, for his first goal of the campaign.
It was also the first league goal Albion had conceded at The Hawthorns this season, much to the disgust of Mowbray, who bemoaned his side's defending from the dug-out.
Buoyed by their goal, Rangers grew in confidence as the half progressed and when Sahar cut in from the left flank on the half hour, his fearsome drive flew a yard or so wide of Kiely's left hand post.
The Baggies were equally as impressive on the counter-attack though and when James Morrison left Chris Barker trailing in his wake down the right flank, he cut and inside and was only denied by a first class save from Camp.
The ensuing corner almost resulted in goal number four, but Leon Barnett saw his towering header cleared off the line by Moore, and then Phillips was denied by the same player, albeit at the second attempt.
Camp had to be at his agile best to thwart Miller in the 40th minute, but he was powerless to prevent Phillips making it 3-1 just 30 seconds later.
Greening slipped a neat pass into the path of the Baggies top-scorer on the edge of the penalty box and he did the rest, curling a textbook right footed effort beyond the R's number one and into the top corner of the net.
John Curtis replaced Rehman at the resumption, with the summer signing slotting in at right back.
Rangers were very nearly gifted a second goal in the 49th minute, when Paul Robinson's misplaced pass put Barnett under pressure and his clearance from inside the box cannoned back of Sahar and into the grasp of the grateful Kiely.
Curtis was booked for two fouls in as many minutes on danger-man Filipe Teixeira, before Morrison sent a fizzing volley on target, which Camp gathered at the second time of asking.
Albion put the result beyond all doubt in the 57th minute.
Camp produced heroics to save Phillips' initial effort, but when Danny Cullip's clearance landed at the feet of Koren, his fearsome strike from 18-yards whistled past the startled R's custodian.
Moments after Camp tipped Robinson's goal-bound header over the bear, the hosts made it five - courtesy of another wonder-goal.
Blackstock's clearance from yet another Albion corner appeared to be adequate enough, but when Greening arrived bang on cue to meet the ball on the volley, Camp stood motionless as it rocketed into the bottom corner.
Rowlands did his utmost to reduce the arrears when he had two efforts saved in as many minutes by the otherwise untested Kiely, but it was Albion who finished in the ascendancy, with second half substitute Craig Beattie having a goal incorrectly ruled out for offside in the dying moments.
WBA: Kiely, Hoefkens, Robinson, Barnett, Koren, Greening (Gera 68), Albrecthsen, Miller (Beattie 68), Teixeira (Brunt 63), Phillips, Morrison.
Subs: Steele, Pele.
Scorers: Phillips 17 & 40, Miller 18, Koren 57, Greening 65
QPR: Camp, Barker (Bignot 60), Cullip, Stewart, Bolder, Blackstock, Ainsworth, Rowlands, Sahar (Ephraim 60), Moore, Rehman (Curtis 46).
Subs: Cole, Timoska.
Scorers: Ainsworth 24
Bookings: Curtis 51, Rowlands 82
Referee: Mr A P D'Urso
Attendance: 24, 757
