West Ham fell to a fourth consecutive Premier League defeat on Sunday afternoon as they were beaten 3-0 by Southampton.
Slaven Bilic had made just two changes from the 4-2 defeat to West Brom last weekend, but went behind in the 40th minute after the in-form Charlie Austin scored his fifth goal in four games in all competitions for the Saints.
The visitors then doubled their lead just after the hour mark as Dusan Tadic nicked past goalkeeper Adrian and tapped into an open net before James Ward-Prowse rounded off the scoring in the second minute of injury time.
West Ham remain in the relegation places, sitting in 18th on three points, while Southampton move up to ninth with eight points after their victory.
The first half was a mostly quiet affair with neither side having many clear-cut chances, although West Ham did have a penalty appeal turned down in the 17th minute when Simone Zaza went down under pressure from Cedric Soares but referee Jon Moss waved away the calls.
Twenty minutes later, the first chance of the half emerged as Dimitri Payet knocked in a corner that was headed on by Zaza at the near post and looked destined for Michail Antonio, but he couldn't get to the ball in time and it flashed across the face of the goal.
But Southampton broke the deadlock with five minutes of the half to play, as Steven Davis found Tadic on the left flank who in turn played in an onrushing Bertrand. The defender then crossed for Austin, who made no mistake in sliding home to score in his fourth consecutive game in all competitions.
Southampton could have had a second just before half-time, with Nathan Redmond forcing a save from the West Ham goalkeeper before Cedric smashed the side netting with a close-range effort.
The visitors, buoyed by their late first-half goal, started well in the second half with Adrian again called into action, saving from a looping Jose Fonte header before Tadic tried his luck - but the Serb could only find the feet of the Hammers stopper.
West Ham had a second penalty appeal waved away by referee Moss and Zaza was the felled man once again, although Oriol Romeu just pulled out of the tackle as the striker went down leading to a simulation booking for the Italian.
Southampton doubled their lead in the 62nd minute, as Redmond won the ball from Cheikhou Kouyate and found Austin, who took one touch to chip the ball into the path of Tadic. The midfielder then rounded the onrushing Adrian and stroked home into an open net.
But the Hammers had their chances to get back into the game, with the subdued Payet poking an effort off target after a great break from Antonio, before Virgil van Dijk cleared an effort from Zaza off the line.
Adrian continued to face pressure from the Saints though, keeping out stinging efforts from Ward-Prowse and Pierre-Emile Hojbjerg but he couldn't stop a second effort from the former. Redmond picked out a gut-busting run from Davis into the box, who knocked the ball into the path of Ward-Prowse and he obliged by slotting it into the back of the net.
It rounded off another bad day at the office for West Ham, who have now lost five of their opening six Premier League games for the first time in their history.
Player ratings
West Ham: Adrian (7), Nordtveit (6), Reid (6), Ogbonna (6), Arbeloa (6), Antonio (7), Kouyate (6), Noble (6), Lanzini (5), Payet (6), Zaza (6).
Subs used: Fernandes (4), Feghouli (5), Fletcher (4).
Southampton: Forster (6), Cedric (7), Fonte (7), Van Dijk (8), Bertrand (7), Davis (7), Tadic (7), Romeu (7), Hojbjerg (7), Austin (8), Redmond (7).
Subs used: Ward-Prowse (6), Long (6), Martina (n/a).
Man of the match: Charlie Austin