Manchester United have sacked Jose Mourinho after Sunday's defeat at Liverpool left the club 11 points adrift of the Premier League top four.
Mourinho, 55, departs Old Trafford after two-and-a-half years with United sitting sixth in the table, and with only one win in the league since Nov. 3.
He was informed of the decision at the club's Carrington training ground on Tuesday, with executive vice chairman Ed Woodward delivering the news in person around 9:30 a.m.
The club are closing in on the appointment of former striker Ole Gunnar Solskjaer as interim boss, provided they can agree terms with Norwegian club Molde, but Tottenham manager Mauricio Pochettino remains the firm favourite for the role on a permanent basis.
Mourinho said his goodbyes to several staff members, and some United players went into his office to see him, although it is unconfirmed which players they were.
The United playing staff were not told directly about the decision to sack Mourinho by the club, with many finding out through the media. Sources have also told ESPN FC that Mourinho has not yet said goodbye to the players.
Sources have confirmed that Woodward spoke with United owner Joel Glazer on Monday, the day after United's defeat to rivals Liverpool, although the decision to part company was not based on that result.
The United board decided to act after growing frustrated with Mourinho's performance in a number of areas, notably first-team results, transfers, development of youth and style of football.
Mourinho, who was said to be completely surprised by the decision, also made it clear that he was unwilling to work with a director of football at Old Trafford, an appointment Woodward is keen to push through in 2019.
Assistant Michael Carrick and academy chief Nicky Butt will take over in the interim, although there is no indication that the pair will be in charge for United's next game against Cardiff on Saturday.
A caretaker manager will be appointed until the end of the current campaign, with a permanent manager put in place ahead of next season.
Pochettino is the preferred choice as permanent boss, although there is an acceptance that Spurs chairman Daniel Levy will fight to keep a coach who has guided the club to three consecutive top-three finishes.
The interim caretaker appointment is likely to be from outside the club and within the next 48 hours, with former player Solskjaer now at the top of United's list, according to ESPN sources. Former United defender Laurent Blanc discussed as possible candidates internally in recent weeks.
A statement issued on Tuesday morning read: "Manchester United announces that manager Jose Mourinho has left the club with immediate effect. The club would like to thank Jose for his work during his time at Manchester United and to wish him success in the future.
"A new caretaker manager will be appointed until the end of the current season, while the club conducts a thorough recruitment process for a new, full-time manager."
Mourinho took charge of United in the summer of 2016 following the departure of Louis van Gaal, winning the Europa League and EFL Cup in his first season.
But although United finished second in the Premier League last season, they were a distant 19 points behind champions Manchester City, lost to Chelsea in the FA Cup final and were knocked out by Sevilla in the round of 16 of the Champions League.
Mourinho signed a contract extension in January that could have kept him at Old Trafford until 2021, but there were always growing concerns at board level that no one should feel "they are bigger than the club."
He has cut an increasingly frustrated figure over the past year -- particularly after the failure to sign a centre-back in the summer.
Mourinho has had high-profile spats with key players, most notably Paul Pogba, throughout 2018, culminating with the France international being stripped of the vice captaincy in September. Pogba has not been in the United team for the past four Premier League fixtures.
News of Mourinho's dismissal had a positive impact at the New York Stock Exchange on United's share price, which increased in value by almost six percent and had a day high of $18.39.