Roberto Di Matteo says he is "extremely surprised and disappointed" after being sacked by struggling West Brom on Sunday.
The Baggies placed their Italian manager on gardening leave after their 13th defeat in 18 games, Saturday's 3-0 reverse at Manchester City, left them outside the Premier League relegation zone on goal difference alone following Birmingham's victory at West Ham on Sunday.
In addition, Di Matteo's assistant Eddie Newton and head of sports science Ade Mafe have left the club, with first-team coach Michael Appleton taking over on a caretaker basis while a new manager is sought.
A statement released by Di Matteo through the League Manager's Association read: "I was extremely surprised and disappointed to be relieved of my duties today.
"Winning promotion to the Premier League with West Brom last season was without doubt one of the highlights of my career and certainly my managerial career.
"Playing in this league is tough and we have had to compete against some fantastic sides but we have shown that we can compete with the best. Apart from the first week of the season, the club has not been in the bottom three and has an important run of home fixtures coming up. I am disappointed that I don't now have the chance to lead the team through this crucial period and keep them in the league.
"I wish the players well over the coming weeks and I thank them for the hard work they have put in and the great attitude they have shown. I would like to thank the staff at the club and of course the most loyal and fantastic fans, with whom I had a great relationship during my time at the club."
Albion chairman Jeremy Peace earlier said: "This has been a tough decision but we, as a board, believe it is the right one to give the club the best possible chance of remaining in the Premier League.
"Our poor sequence of results stretches back more than three months and there has been little sign of it coming to an end.
"If this run continues much longer, achieving our goal of retaining our Premier League status will become increasingly difficult. That is why we felt compelled to act now."
The LMA themselves hit out at the sacking, with chief executive officer Richard Bevan saying: "Roberto represents yet another victim of the 'hire and fire' mentality that pervades in our game.
"The club has big games ahead, against Wolves and West Ham, and you have to question the decision to sack the manager. It is in exactly situations like these that we all want to see clubs back the individuals they have employed rather than see the sack as a quick-fix panacea.
"In West Brom's case that means showing support and loyalty to the manager that brought the club automatic promotion back to the Premier League last season, at the first time of asking, and was the league's manager of the month only four months ago."
But Peace defended the club's approach and said: "This club's track record proves we do not take such decisions lightly, with Roberto being only our fourth manager or head coach in almost 11 years."
Albion lost just two of their first nine league games following their return to the Premier League in the summer.
But they have won just three times since, losing five successive league games prior to a 3-2 win over Blackpool and also taking just one point from their last three games.
Peace continued: "On behalf of the board, I would like to thank Roberto for his efforts over the past 19 months, particularly for his contribution towards last season's promotion success and our very promising start to the current campaign. We wish him and his family well for the future.
"Roberto embraced the structure in which we wanted him to work and he has been a good colleague.
"However, we are in a results-driven industry and felt we had no choice but to act now."