AC Milan fired Massimiliano Allegri and put former assistant coach Mauro Tassotti temporarily in charge, a day after an embarrassing 4-3 loss at promoted Sassuolo.
Langishing in 11th place - six points above the relegation zone - Milan announced the move on its website.
Milan has won only five of 19 matches this season and Allegri had already announced over the winter break that he would leave at the end of the season.
But the loss to Sassuolo, which got four goals from teenage forward Domenico Berardi, hastened his departure.
As soon as the match ended, Milan general manager Barbara Berlusconi said the loss highlighted the need for urgent change.
Allegri took over Milan in 2010 and won Serie A in his first season then finished second and third the past two years.
Still, he never became a favorite of club owner Silvio Berlusconi.
The only other trophy Allegri won with Milan was the 2011 Italian Super Cup.
However, Milan was the only Italian club to reach the knockout stage of this season's Champions League, and will face Atletico Madrid next month.
The 53-year-old Tassotti is a long-time Milan assistant who had a 17-year playing career with the club.
Allegri's contract was due to expire at the end of this season.