Nottingham Forest have parted company with manager Aitor Karanka after just a year in the job.
The 45-year-old Spaniard was appointed in January 2018 and has left the City Ground with Forest seventh in the Championship table.
His final game in charge was Saturday's FA Cup defeat by Chelsea, having beaten Leeds the previous week to move within four points of the top six.
A club statement said Karanka "asked to be released from his contract".
It added that Forest had agreed to his request and first-team coach Simon Ireland has been put in caretaker charge of the team.
Forest, who are away at Reading on Saturday, are now looking for their 11th full-time manager since June 2011.
Karanka arrived at Forest on a two-and-a-half year deal after being sacked by Middlesbrough in March 2017, having guided them promotion to the Premier League in 2015-16.
He was backed financially in the summer, signing Benfica midfielder Joao Carvalho for a club-record fee of £13.2m and striker Lewis Grabban for a reported £6m.
However, rumours surfaced surrounding the former Real Madrid coach's future in December, when Forest slipped out of the play-off places during a run of five games without a win.
His side were 3-0 up at Norwich but surrendered the lead to draw 3-3, lost at struggling Millwall and were beaten at home by Preston and QPR.
'Yet another season of change'
Analysis: Colin Fray, BBC Radio Nottingham
It seems there's been some falling-out and disagreements behind the scenes, and this has been speculated on in public since Boxing Day, when it was our understanding he was on the brink of going at that point.
He's held on for another 10 days or so before it has come to a head over the past couple of days.
Exactly what the disagreements are about is unclear but it's been fairly obvious for a month or so before Christmas that Karanka wasn't entirely happy with life at the City Ground.
Many fans will see it as a huge shame because he had a huge groundswell of support. A lot of Forest supporters really didn't want to change in the middle of the season again, and it still means that the last time they started and ended a season with the same manager was in 2010-11.
When a lot of fans believe the club needs stability, it's yet another season when they have to make a change.