Jarrod Bowen has apologised to West Ham supporters for the "embarrassment and pain" caused by Premier League relegation.
West Ham's 14-year stay in the top flight was ended on Sunday after their 3-0 win over Leeds came too late in a miserable season to overhaul Tottenham.
Their drop into the Championship comes three years after the club's greatest achievement of the modern era, when Bowen's goal in Prague saw them beat Fiorentina to lift the Conference League title.
"It's hard to post something like this when all you're feeling is embarrassment and pain," the West Ham captain posted on Instagram.
"I could write loads trying to explain where it all went wrong this season, but honestly what you deserve from me is an apology.
"Winning that trophy in Prague was the best night of my career. Sunday was the worst.
"We just weren't good enough. Simple as that. And that's why the season ended the way it did."
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Nuno Espirito Santo, who took over in September with the team 19th, is expected to depart this week following meetings with the club hierarchy.
"To the fans, you didn't let us down once," Bowen said. "The support home and away never changed, even when things weren't good enough from us on the pitch. We should have given you more. You deserved more.
"One thing I know about this club is that it has the desire and fight to bounce back from this. This club belongs in the Premier League and deserves to be back there as soon as possible."