Roy Hodgson's first game in charge of Crystal Palace ended in a 1-0 home defeat as an early Steven Davis strike sealed the points for Southampton and the Londoners made it five Premier League matches without a goal.
Palace made a positive start as the former England manager looked on from the home dugout, with Christian Benteke getting down the left and swinging in a cross that caused problems before being cleared.
But after only six minutes, the struggling Eagles were behind as Davis played in Dusan Tadic down the right and, when his cross was pushed out by Wayne Hennessey, Davis followed up to sidefoot into the corner.
Davis was soon involved again when his cross was headed over by Shane Long, but Palace began to come back and should have levelled when, with just over a quarter of an hour played, Benteke failed to connect cleanly with a chance and Fraser Forster parried.
Hennessey then had to hang on as Saints' Nathan Redmond let fly from the edge of the area soon afterwards, but Palace countered again and, with half an hour gone, Loftus-Cheek was only just off target with a fierce effort from 20 yards.
Moments later, the same player saw a strike deflected behind after a fine run, but Southampton soon sprang to the other end where Tadic wasted a crossing opportunity with a tame ball in.
Redmond then sent another strike from distance straight at Hennessey but the last chance of a bitty opening period fell to Townsend, who sent a dipping angled shot over Forster's crossbar.
Palace must have been wondering what they had to do to score when, in the opening minutes of the second half, a Loftus-Cheek cross somehow evaded everyone before Jason Puncheon saw a close-range effort stopped by Forster.
Redmond had an effort blocked amid a scramble inside the Palace penalty area, and as the rain began to teem down in south London Long did well to hold up an early ball forward, helping the Saints win a corner that came to nothing.
Benteke steered a header over as Palace looked to find some spark, but they were struggling to manufacture clear sights of the Southampton goal and, when Loftus-Cheek crossed towards Benteke, Wesley Hoedt was on hand to prevent the ball from reaching him.
As the game entered its closing stages, Southampton's Mario Lemina almost created enough space for himself to shoot as the visitors sought the second goal that would seal the points, but was crowded out.
With three minutes to go Virgil van Dijk came on for his first appearance since a summer move to Liverpool fell through, and Southampton saw out the closing stages to secure a valuable away victory.