Winston Reid admitted Southampton worked harder than West Ham during the painful 3-0 defeat at the London Stadium.
The Hammers are enduring their worst start to the season since 2002 -- when they were relegated -- after slumping to a fifth loss in their opening six matches.
Fingers are being pointed at West Ham's defending after goals from Charlie Austin, Dusan Tadic and James Ward-Prowse made it 14 conceded in their last four Premier League games.
"When you lose you, you can always do more," Reid told the club website. "We've played against good teams so far and we need to work a lot harder to get a bit of luck on our side.