Watford announced on Sunday they had dismissed manager Marco Silva, blaming an "unwarranted approach" by Premier League rivals Everton for a downturn in results and loss of focus.
The Portuguese manager was a target for the Merseyside club earlier in the campaign after an excellent start to the season but a run of one win in 11 Premier League matches has cost him his job.
Instead, Everton appointed Sam Allardyce to replace the sacked Ronald Koeman.
"The club is convinced the appointment of Silva was the right one and had it not been for the unwarranted approach by a Premier League rival for his services we would have continued to prosper under his leadership," Watford said in a statement.
"The catalyst for this decision is that unwarranted 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 FC has been jeopardised."
The club are 10th in the Premier League table but only five points clear of the relegation places.
"For the security and success of the football club, the board believes it has to make a change," Watford's statement said.
"The club will seek to make a swift appointment and there will be no further comment until that appointment has been made."
Silva, who was in charge at Hull City when they were relegated last season, is the eighth Premier League manager to lose his job this season.