Head coach Carlos Carvalhal has left Sheffield Wednesday by mutual consent.
The Portuguese arrived at Hillsborough in the summer of 2015 and steered the Owls to the Championship play-off final at the end of the 2015/16 season.
A second play-off campaign followed in 2016/17 but Wednesday were beaten at the semi final stage by Huddersfield.
This season, the Owls have slipped to 15th in the table at the halfway stage and Carvalhal has departed following the 2-1 home defeat to Middlesbrough on Saturday.
Chairman Dejphon Chansiri told swfc.co.uk: “I would like to offer my sincere thanks to Carlos for the time, effort and commitment he has given Sheffield Wednesday over the last two and a half years.
“Both parties believe the time is right to go our separate ways.
“I maintain a huge amount of respect for Carlos as a coach and as a person and he will always be welcome at Hillsborough.
“I wish him every success in the future.”
Lee Bullen will take charge of the team for the trip to Nottingham Forest on Boxing Day and until a permanent appointment is made.
The club will be making no further comment at this time.