West Ham co-owner David Gold admitted he wished he had done things differently following the club's relegation from the Barclays Premier League and the sacking of manager Avram Grant on Sunday.
The Hammers went down after squandering a 2-0 lead at fellow strugglers Wigan to lose 3-2. Just over an hour after the final whistle at the DW Stadium, the club confirmed they had parted company with Grant and that first-team coach Kevin Keen would take charge for their final match of the season against Sunderland at Upton Park next Sunday.
Gold wrote on Twitter: "I honestly believed with the players we brought in in January, plus the imminent return of (Thomas) Hitzlsperger, we had done enough to pull clear of danger."
He added: "I know that Scotty Parker shared that belief with me and we both had confidence that we would retain our Premiership status. This is undoubtedly the worst moment in all the years I've been supporting West Ham and of course I wish I'd done things differently."
After succeeding Gianfranco Zola, Grant oversaw four defeats in his first four league games, a sequence which set the tone for the rest of the campaign. There was a brief revival when West Ham took 10 points from five fixtures between February 2 and March 5, including a memorable 3-1 home victory over Liverpool.
By that stage Grant had used the transfer window to sign striker Demba Ba and acquire Robbie Keane and Wayne Bridge on loan, while Hitzlsperger, who joined the club the previous June, made his long-awaited debut after recovering from injury.
However, the Hammers lost inspirational midfielder Parker to an Achilles problem last month, and did not have enough to get themselves out of trouble, with Sunday's sixth defeat in seven league games sealing their fate.
In his post-match press conference, Grant had accepted responsibility and apologised to the club's supporters. "I will not speak too much about the unbelievable problems we have had this year and other things because it is a game of results," the 56-year-old Israeli said.
"My job was to keep the team in the league and I didn't do it. Many things were good, but at the end of the day football is a game of results and the results are my responsibility. So many supporters came, it was great, unbelievable, and they have been good to me all season. I wanted so much for them that we could do better. I am very sorry about this."
Needing a win to stand any chance of beating the drop, West Ham went 2-0 up through headers from Ba in the 12th and 26th minutes. But the Latics stormed back after the break, Charles N'Zogbia scoring either side of a Conor Sammon strike to keep the hosts' survival hopes alive.