Paul Heckingbottom has become the first Premier League manager sacked this season after Sheffield United fell to the bottom of the table.
A 5-0 loss to fellow strugglers Burnley proved the final straw for Blades bosses, who have quickly announced the return of former manager Chris Wilder.
United chief executive Stephen Bettis said in a statement on the club website: "Firstly, on behalf of the board of directors, I'd like to thank Paul for all of his efforts at Sheffield United, firstly as U23s manager before stepping up to take control of first-team duties.
"His professionalism and dedication have been a credit to the club and I'm sure all Unitedites enjoyed the promotion-winning campaign.
"However, after slipping to the bottom of the table and a number of disappointing results and performances, it is felt that a change is needed to give the club a boost and every possible chance of remaining in the Premier League beyond this season."
Heckingbottom, who was appointed on a permanent in November 2021, guided the club to promotion last term but a torrid start to the season has included an 8-0 home thrashing by Newcastle and a 5-0 defeat at Arsenal.
First-team coaches Stuart McCall and Mark Hudson have also left the club ahead of Wednesday's home game against Liverpool.
Sheffield United say they hope to have a new manager in place before Liverpool visit.
Club owner Prince Abdullah told talkSPORT on Tuesday that Wilder was "the best guy on planet earth to take over the club right now in these circumstances".
He said: "Chris is very optimistic he can save the season, he doesn't think it's easy, but he thinks it's still possible.
"When you look at the table it's a very special year, a very weird year when it comes to the standings, so it's still early, the season is still long and we have every chance to achieve our goals."
