Newcastle United managing director Lee Charnley insisted "the process of scrutinising" has already begun after the club were relegated from the Premier League.
Not even the late appointment of former Real Madrid coach Rafael Benitez could save Newcastle, who will drop to the second tier of English football after arch-rivals Sunderland defeated Everton 3-0 on Wednesday.
Sunderland's victory ensured they cannot be overhauled in 17th position heading into the final game of the season, with Newcastle and Norwich City now preparing for life in the Championship.
Benitez's future is now the subject of intense speculation and Newcastle - who bounced straight back up as champions following their previous relegation in 2008-09 - released a statement via Charnley shortly afterwards, apologising to their fans.
The statement read: "We are devastated at our relegation from the Premier League, as I know every single person connected to this football club will be.
"I want to thank all of the fans for the support you have shown for the club you love throughout the season, in spite of this massive disappointment and underachievement.
"Your support throughout has been magnificent, but I want to pay particular thanks for the incredible backing you have given to Rafa and the team during the latter part of the season. Nothing more could be asked of you and I am truly sorry we have not given you the outcome you deserve.
"I also want to thank every single member of staff here. This club is their livelihood, but they are fans too. To go through the threat of relegation last season and then to suffer a worse fate this time around has been very hard for them. I know that each and every one of them has done whatever they could to help us out of the situation we now find ourselves in.
"We know that supporters want to know what the future holds and will want to hear more from us as soon as possible. The process of scrutinising what went wrong and planning for what is to come has already begun.
"Right now, of course, Rafa and the team must prepare for the final game of the season but after that, please rest assured we will communicate more fully with supporters."
