Watford have sacked manager Marco Silva, blaming Everton's approach for the Portuguese in November as the "catalyst for this decision".
The Hornets have won one of their last 11 Premier League games and are 10th in the table, five points above relegation after Saturday's 2-0 loss at Leicester.
Spaniard Javi Gracia was announced as Silva's replacement on Sunday evening.
Gracia, 47, left Russian club Rubin Kazan in June after a 10-year coaching career in his homeland and in Greece.
He is the 10th manager to work at the club under the Pozzo family since 2012.
"This has been a difficult decision and one not taken lightly," the club added.
"The catalyst is that approach, something which the board believes has seen a significant deterioration in both focus and results to the point where the long-term future of Watford has been jeopardised."
Everton have yet to respond.
Silva has become the eighth Premier League manager to lose his job this season following changes at Crystal Palace, Everton, Leicester City, Stoke, Swansea, West Brom and West Ham.
|Silva record before and after Everton approach|
|Games||Wins||Draws||Losses||Goals for||Goals against||Win %|
What happened with Everton and Silva?
Dutchman Ronald Koeman was sacked by Everton on 23 October - fewer than 24 hours after a 5-2 home defeat by Arsenal left them in the Premier League relegation zone. That was despite spending £140m in the summer.
Everton were understood to be willing to pay about £10m in compensation for Silva, who signed a two-year contract with Watford in the summer after leaving relegated Hull City at the end of last season.
Previously, Silva guided Olympiakos to the Greek title and claimed a Champions League group-stage victory at Arsenal in September 2015, having already tasted Portuguese Cup success with Sporting.
At the time of Everton's interest, Silva declined to pledge his long-term future to Watford both before and after the home win against West Ham United on 19 November - but the Hornets still made it clear they were unwilling to release
At the time of the approach, Silva said: "I don't want to talk about Everton. It's not where I work. It's a big club, nothing more."
He later said that the speculation was "not a problem" for him and that "this type of interest in players and coaches happens but it is not fair to question our commitment".
Under-23 coach David Unsworth spent five weeks in temporary charge at Everton before Sam Allardyce was eventually appointed on 30 November.
Do the stats back up Watford's claims?
The graph above shows the amount of points the seven top flight teams have earned before and after parting company with their managers.
Frank de Boer was sacked by Crystal Palace in September after only 77 days in charge and no points on the board, Craig Shakespeare left Leicester just four months after signing a three-year permanent deal in October, Ronald Koeman was sacked by Everton later that month and West Ham dismissed Slaven Bilic in November.
Also in November, former Stoke boss Tony Pulis was replaced at West Brom by Alan Pardew, Paul Clement was dismissed as Swansea manager in December, while Mark Hughes was replaced by Paul Lambert at Stoke. Lambert has only been in charge for one game, which he won against Huddersfield.
BBC Three Counties Radio sports editor Geoff Doyle:
There has been friction for some time between Marco Silva and those on the board so the worrying dip in Premier League form meant this was only ever going to end one way.
Watford have blamed Everton's approach for Silva, but the first sign of trouble was at the end of August when winger Nordin Amrabat was allowed to leave. Silva was annoyed and hadn't agreed. He let his feelings be known but the response was 'did he not understand the Watford model' in which technical director Filippo Giraldi and the board make the transfer decisions? Was he led to believe he would have more of a say?
Silva has blamed injuries for the bad run of late. He wanted players in this month but the board disagreed and the tension mounted. Silva said the club had to 'grow up' by getting things right behind the scenes. Defeat at Leicester was the final straw for the board with relegation on their mind. New players are desperately needed but if the board didn't trust Silva then why give him players he wanted?
Will top managers/coaches steer clear with this model in place? A model in which the head coach doesn't have as much control as he wants and inevitably leads to friction?