West Ham captain Declan Rice described his side's 4-0 Premier League loss to Brighton as "demoralising".
The Hammers remain two points above the bottom three after an abject second-half display at Amex Stadium.
"That wasn't a performance that was acceptable at all," England midfielder Rice told Sky Sports.
"I got a yellow late on, I could've got another one and I never want to feel like that on a football pitch. We've let the fans down massively."
He added: "Credit to Brighton, they played us off the pitch. I know it's cliched to stand here and say it's not good enough but on days like today you have to apologise to the fans.