Southampton boss Ralf Hassenhuttl says the Saints' defenders, and not Irish prospect Will Smallbone (inset), have to take the blame for their collapse at West Ham.
A goal from Dublin-born striker Michael Obafemi, one of three Irish players in the Southampton side, had the Saints level at 1-1 away to the Hammers, who again left Darren Randolph on the bench.
But a goal either side of the break gave West Ham their first win in eight league games.
Smallbone, capped at youth level by Ireland, was playing in only his second Premier League game but Hassenhuttl said the loss was not down to him. "Will wasn't the problem," said Hasenhuttl. "He had the power and the way for us is to force these young players even in tough games because it shows how far they have to go.
"I think he did a good job and it was not his fault that we had a problem with long balls. We had more problems with the centre-back positions, which is why I changed it to a back five."