Aitor Karanka has left his role as Nottingham Forest manager after asking to be released from his contract.
Karanka has found himself under pressure in recent weeks, despite Forest sitting seventh in the Sky Bet Championship, just four points off the play-offs.
Sky Sports understands he decided to leave the City Ground due to outside influence disrupting his day-to-day team management.
Karanka is also believed to have felt the lack of stability, control and constant speculation was affecting the club's progress and players' mentality.
He is also believed to feel the only support he got from the club was from the fans but felt the constant outside influences when preparing for a game and on match day itself gave him no choice but to resign.
It is also understood Karanka is keen to get back into management as soon as possible.
The 45-year-old Spaniard took over at the City Ground in January 2018, succeeding Mark Warburton in the role.
Karanka previously spent just over three years as Middlesbrough boss and was also assistant manager at Real Madrid.
His last game in charge of Forest came in the 1-0 defeat to Chelsea in the FA Cup last weekend, before which he guided them to a 4-2 win over league leaders Leeds.
Prior to that they picked up just two points from their last five games, a run that included surrendering a three-goal lead to draw 3-3 with Norwich on Boxing Day.
"Aitor Karanka has asked to be released from his contract as the manager of Nottingham Forest Football Club," read an official statement.
"The club have agreed to this request and the terms of departure have been agreed. Both parties wish each other every success for the future.
"There will be no further comment from either party.
"Simon Ireland will take charge of first-team affairs until a new manager is appointed."
Nottingham Forest play Reading at the Madejski Stadium on Saturday.