The fine margins of life in the Sky Bet Championship were evident in West London in a game that hinged on 100 seconds of action.
With City heading towards a rare goalless draw, a quick counter-attack sent Lee Tomlin across the halfway line with purpose and feeding the run of Bobby Reid.
Reid did the first bit brilliantly, turning inside the last defender, only to be thwarted by a stunning save from Alex Smithies.
No sooner had the home team regrouped than they struck the winning goal themselves, as Idrissa Sylla finished from close range at the end of another swift breakaway, condemning City to back-to-back defeats in the process.
Lee Johnson made four changes to his side after falling to a first loss in six matches in the Severnside derby at Cardiff on Friday night.
Adam Matthews, Josh Brownhill, Callum O’Dowda and Reid were all recalled, with Mark Little, Marlon Pack, Luke Freeman and Jamie Paterson making way.
It was Tomlin who handed City a lifeline in South Wales with a stunning strike to halve the deficit, and the maverick forward was at it again in the early stages at Loftus Road.
This time it was a cheeky nutmeg that created something from nothing. As Tomlin raced into the box, it would take a vital interception to prevent him squaring the ball for Tammy Abraham, who was lurking with intent on the edge of the six-yard box.
QPR were without a home win in the league since the opening day of the season, but did show glimpses of their attacking threat from set-pieces as both Sylla and Steven Caulker headed over from corners.
Then Massimo Luongo forced a first notable save when his left-footed shot at the end of a driving run was pushed well clear of danger by Frank Fielding.
Luongo, a key man for Swindon Town in the 2014/15 League One promotion race, was proving a handful.
Again he broke forward from a deeper position after he was only half-stopped by Hordur Magnusson, who was grateful to Matthews for getting his foot in with a crucial sliding tackle to halt the midfielder in his tracks.
Meanwhile, City remained dangerous – particularly through Tomlin. When Joe Bryan dispossessed Tjaronn Chery and found the number ten, it would take an excellent sprawling save from Smithies to keep his left-footed daisy-cutter at bay.
Tomlin did find the desired bottom corner soon after from Gary O’Neil’s clever scoop over the defence, only to be flagged offside.
It was a game short of clear-cut chances but not lacking openings to create them.
Both QPR full backs were involved when James Perch’s teasing cross ran right across the danger zone, before substitute Nicholas Hamalainen tried his luck with a low drive that deflected wide at the end of the same attack.
But it was City who would create the best opportunity of the half seconds before the interval.
It was no surprise to see Tomlin involved, picking out Brownhill with a ball over the top that the midfielder helped on to Abraham, who struck it first time but uncharacteristically off target as his shot flew past the post from 18 yards with only Smithies to beat.
With the match hanging in the balance, it was the hosts who began the second period on top.
Fielding had to get down smartly to keep out Chery and Ben Gladwin, while only the crossbar prevented Conor Washington finding the net after his 20-yard shot took a wicked deflection off Aden Flint.
Perhaps concerned by the home team’s physicality, Johnson reacted with a double change just shy of the hour, introducing extra height in the form of Pack and Aaron Wilbraham as Brownhill and O’Dowda made way.
Ironically it was from one of many QPR corners that City came so close to breaking the deadlock with 17 minutes left.
Tomlin, less influential since the break and controversially booked for an alleged dive on the edge of the QPR box, led the counter-attack and waited for support from Reid, eventually finding him with a perfect pass.
It was a lung-busting run from the Bristolian, carrying him over the halfway line and into the Rangers penalty area, where he brilliantly turned inside the last defender only to be denied by Smithies’ outstretched left hand.
In cruel fashion, after City’s resulting corner was dealt with, the hosts took the lead themselves as Perch’s cross was clinically dispatched by Sylla at the near post.
It was hard on Johnson’s men in an even contest. The visitors pressed relentlessly in the closing stages, forcing a series of late corners, but Wilbraham could not quite climb high enough to head home Tomlin’s enticing cross and Abraham glanced Freeman’s delivery on to the top of Smithies’ net.