The futures of both managers 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 R's 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.