The futures of QPR boss Mark Hughes and Saints counterpart Nigel Adkins were subject to intense speculation in the build-up to a Loftus Road encounter contested by the sides bottom and second-bottom of the standings.
QPR and Southampton had conceded 49 league goals between them prior to the game and the hosts' defence was breached 23 minutes in as Rickie Lambert bundled home his fifth of the season.
The Rs found themselves further behind at the end of the first half as man-of-the-match Jason Puncheon returned to haunt the club he spent a loan spell with last season, striking home from the edge of the box.
Boos rang around Loftus Road at the half-time whistle and the hosts came out rejuvenated for the second period, with Junior Hoilett clawing one back four minutes in.
That, though, was to be as good as it got for QPR as Southampton wrapped up victory when Anton Ferdinand deflected home Morgan Schneiderlin's late cross.
Both managers stuck with the same starting line-ups that played last weekend for Saturday's crunch match between the Premier League's two worst sides.
An impressive 3,203 visiting fans crammed into the School End and enjoyed a bright, if fruitless, opening spell.
Southampton were quicker to settle and captain Adam Lallana came close in the seventh minute, firing just over after a neat one-two with Gaston Ramirez.
Just as a chorus of 'One Nigel Adkins' ended, Saints had another chance as former QPR loanee Puncheon's cross evaded Lallana in the box and clipped the far post.
While the visitors were enjoying the lion's share of possession, they were still looking shaky at the back.
Adel Taarabt - so often a threat for QPR - highlighted that defensive fragility by breaking through in-between Nathaniel Clyne and Jose Fonte, before forcing Paulo Gazzaniga into a quick reaction save.
The Argentinian goalkeeper did not fare so well with a Hoilett shot less than a minute later, somewhat fumbling a parry behind.
Saints returned to the attack in the 22nd minute, when Lallana's dangerous ball across the six-yard box was cleared behind for a corner from which Lambert saw an effort deflect behind.
He was not to be denied for long, though, and, when the resulting corner was not cleared properly, Ramirez pulled back for Fonte, whose shot was prodded goalwards by Puncheon. That effort was cleared off the line but Lambert showed his strength to bundle home.
Saints continued to press forward after the opener, although their defence was still looking uneasy as Djibril Cisse and Hoilett threatened to level.
Southampton players claimed a handball against Ryan Nelsen and Jack Cork tested Julio Cesar as they pushed for another, which came on the stroke of half-time.
Puncheon started the move on the right and, when he collected the ball from Clyne, turned Alejandro Faurlin to fire home a left-footed strike.
QPR were booed off at half-time after their inept display and Hughes replaced Faurlin with Jamie Mackie when play resumed.
The west Londoners began brightly and, after Gazzaniga dealt with a Cisse volley, they reduced the deficit.
Adel Taarabt floated in a cross and lost his man, allowing Hoilett to nod home unchallenged in the 49th minute.
They were still looking poor, though, and Puncheon forced Cesar to save and then provided a cross that Lambert came close to turning home.
The Saints striker and Schneiderlin were both thwarted with long-range efforts, before Ferdinand did well to stop Ramirez getting through on goal.
Puncheon was far and away Southampton's standout player and was causing the QPR defence no end of hassle.
After scuffing wide, the winger came close with a drilled effort and then saw a low effort from an acute angle tipped wide by Cesar.
Cisse lashed well wide at the other end and, after Jose Bosingwa's substitution was cheered by home fans, he tried to score with an overhead kick.
The game was flowing from end to end and Cesar had to be at his best to deny a Maya Yoshida scissor-kick 10 minutes from time.
Nelsen headed straight at Gazzaniga moments later and then Saints secured victory, with Puncheon playing a short corner to Schneiderlin for the Frenchman's cross to squeeze in off Ferdinand at Cesar's near post.
QPR fans bellowed 'You're only here for the money' at their players and duly booed the side off at the end of the game, while Adkins and the Saints fans celebrated their first points earned away from home.