Claudio Ranieri has been sacked by Leicester City, nine months after lifting the Premier League trophy.
The Foxes are just a single point outside of the Premier League relegation places, having won the title last season.
Sky sources understand the Thai owners have taken this decision with a heavy heart, but felt the possibility of them being relegated was "unacceptable".
The board expected a bounce in form after giving the Italian a public vote of confidence a fortnight ago offering their "unwavering support". But we understand the owners felt there hadn't been a noticeable improvement and were left with no option but to dismiss him.
Leicester have nobody lined up to replace Ranieri, and will begin searching for a replacement on Friday.
Vice chairman Aiyawatt Srivaddhanaprabha said in a statement on Friday evening: "This has been the most difficult decision we have had to make in nearly seven years since King Power took ownership of Leicester City.
"But we are duty-bound to put the Club's long-term interests above all sense of personal sentiment, no matter how strong that might be.
"Claudio has brought outstanding qualities to his office. His skilful management, powers of motivation and measured approach have been reflective of the rich experience we always knew he would bring to Leicester City.
"His warmth, charm and charisma have helped transform perceptions of the club and develop its profile on a global scale. We will forever be grateful to him for what he has helped us to achieve.
"It was never our expectation that the extraordinary feats of last season should be replicated this season. Indeed, survival in the Premier League was our first and only target at the start of the campaign.
"But we are now faced with a fight to reach that objective and feel a change is necessary to maximise the opportunity presented by the final 13 games."
It is expected that caretaker manager Craig Shakespeare will take Friday's pre-match news conference ahead of their Monday Night Football clash when they host Liverpool.
Ranieri, 65, oversaw the greatest shock in top-flight history when he led the club to the Premier League title 298 days ago, but things have unravelled with the club struggling for league form and being knocked out of the FA Cup by League One side Millwall.
Leicester were beaten 2-1 by Sevilla in the Champions League on Wednesday night with Jamie Vardy scoring their goal to give them hope for the second leg.
Sky Sports News HQ reporter Rob Dorsett said: "It's a huge, huge shock and the club reacting like this will be controversial.
"All the supporters have all said they wanted him to stay. All the fans will believe he will go down as a legend but some felt he had lost the dressing room."