Chris Powell has been sacked by Championship strugglers Charlton, Press Association Sport understands.
The Addicks were preparing a statement on Tuesday morning confirming Powell's departure.
The 44-year-old former England defender has been in the job for three years and won the League One title in 2012.
Life in the second tier has been harder, though, and Athletic currently sit bottom of the table, some four points short of safety.
Powell's dismissal comes two days after the FA Cup quarter-final defeat against Sheffield United.
Charlton are due to face Huddersfield in the Championship on Wednesday night.
The news comes less than a week after Powell agreed terms on a new contract with owner Roland Duchatelet.
Powell, whose previous contract was due to run out at the end of the season, revealed last Thursday that a new deal was waiting to be signed, but he was awaiting certain assurances from Belgian businessman Duchatelet.
Those assurances surrounded the recruitment of players after Charlton sold key men Dale Stephens and Yann Kermorgant in January and replaced them with a host of players on loan from Standard Liege, another club owned by Duchatelet.
Powell has only used those players sparingly since their arrival, for example preferring Ben Hamer in goal to January signing Yohann Thuram-Ulien, which may have tried the new owner's patience.
Tuesday's news brings a turbulent campaign to an end for Powell, who had to deal with the ownership saga and the state of The Valley pitch which caused a spate of postponements during the winter which leaves them playing catch-up at the foot of the table.
Former Standard Liege coach Jose Riga, currently a technical director at AC Milan, is being heavily linked with the role.