Head coach Nuno Espirito Santo was sacked by Nottingham Forest early on Tuesday, becoming the first English Premier League manager this season to lose his job.
"The club thanks Nuno for his contribution during a very successful era," said a club statement released just after midnight.
The Portuguese had been in charge for 21 months at the City Ground, but two weeks ago said his relationship with the club's owner, the Greek billionaire Evangelos Marinakis, had deteriorated.
"Nottingham Forest Football Club confirms that, following recent circumstances, Nuno Espirito Santo has today been relieved of his duties as head coach," the club said.
The 51-year-old took charge in December 2023 after Steve Cooper was sacked and went on to save the club from relegation.
Last season the club finished seventh in the Premier League, their highest since 1994/95.
That secured a first European berth in 30 years, with a Europa League place handed to Forest instead of their initial Conference League spot, after Crystal Palace's demotion for breaching Uefa's multi-club ownership rules.
"The club thanks Nuno for his contribution during a very successful era at the City Ground, in particular his role in the 2024/25 season, which will forever be remembered fondly in the history of the club," said the statement
"As someone who played a pivotal role in our success last season, he will always hold a special place in our journey."
POSTECOGLOU IN FRAME
Forest sit 10th in the Premier League on four points after three games, but were soundly beaten 3-0 by struggling West Ham in Nuno's last match in charge.
British media reported that talks had begun to appoint a successor quickly, with former Tottenham Hotspur manager Ange Postecoglou said to be among the candidates along with Crystal Palace's Oliver Glasner and Bournemouth's Andoni Iraola.
Cracks between the owner and head coach began to show in May last season, when Marinakis appeared to confront Nuno on the pitch following a 2-2 draw against Leicester at the City Ground.
Forest later said the owner was frustrated that striker Taiwo Awoniyi had continued to play following an 88th-minute injury but added there was "no confrontation" and to suggest otherwise was "fake news".
Nuno, who also managed Tottenham in 2021, was publicly critical of Forest's transfer activity since the end of last season, which reportedly did not go down well with Marinakis.
Forest brought in 13 players as new sporting director Edu Gaspar took a more hands-on role in signings, but they let several others go, including Anthony Elanga, Danilo and Wayne Hennessey, leaving Nuno to complain his side had become "unbalanced".
"I always had a very good relationship with the owner. Last season we were very close and spoke on a daily basis. This season it is not so well," Nuno said last month of his dealings with Marinakis.
"Our relationship has changed and we are not as close. Everybody at the club should be together but this is not the reality."
Nuno later said he had spoken to Marinakis on the phone since and the two would meet during the international break to iron out their differences.
Sky Sports News reported that the meeting never materialised and Marinakis decided instead it was better to replace Nuno.
Edu and chief football officer Ross Wilson will oversee the appointment of a new head coach.
Forest's next match is away to third-placed Arsenal on Saturday.