Galatasaray has parted company with head coach Hamza Hamzaoglu despite him leading the club to the domestic double last season.
Hamzaoglu took over from Cesare Prandelli in November 2014, initially until the end of the campaign.
However, the former assistant manager of Turkey was rewarded with a long-term contract extension after winning both the league and the cup.
He also steered the team to the Turkish Super Cup at the start of this season.
"Galatasaray football team and Hamza Hamzaoglu have mutually agreed to terminate his contract. We want to thank our former manager for his services to the club and wish him all the best in the future," the club said in a statement.
Galatasaray sits third in the Turkish Super Lig, five points behind league leader Besiktas.
The Istanbul club remains in the running to reach the knockout stages in the Champions League, though it has just won once in four outings in Group C.
Hamzaoglu was also a league champion with Galatasaray twice in his playing career.