West Ham's defensive frailties were again exposed as Southampton inflicted a fourth successive Premier League defeat on Slaven Bilic's side at London Stadium on Sunday.
The Hammers started brightly, but failed to capitalise as Simone Zaza dragged an effort wide before Michail Antonio strained in vain to meet Dimitri Payet's corner as it flashed across goal.
And tWest Ham were left to rue their missed chances as Charlie Austin and Dusan Tadic struck either side of the interval to heap more misery on Slaven Bilic and his side.
Austin swept home Ryan Bertrand's low cross to open the scoring before the visitors pounced on a Cheikhou Kouyaté error, forming a cute exchange of passes to send Tadic in to round goalkeeper Adrian and coolly convert.
Southampton's second sparked West Ham into life as the London Stadium crowd grew frustrated in the late stages in east London.
The hosts were unlucky to be denied a penalty when referee Jon Moss missed Betrand's handball as Sofiane Feghouli's effort cannoned towards goal before Payet sent an effort curling past Fraser Forster's right-hand post from the edge of the box.
Zaza then saw a strike cleared off the line after good work from Payet down the left, but West Ham could not reduce the deficit before Jame Ward-Prowse rubbed salt in the wounds in stoppage time.
