Tottenham have sacked manager Mauricio Pochettino after five years in charge of the Premier League club.
Spurs have made a disappointing start to the current campaign and are 14th in the Premier League.
BBC sports editor Dan Roan believes Jose Mourinho is a strong contender to replace the 47-year-old.
"We were extremely reluctant to make this change. It is not a decision the board has taken lightly, nor in haste," said Spurs chairman Daniel Levy.
"Regrettably domestic results at the end of last season and beginning of this season have been extremely disappointing.
"It falls on the board to make the difficult decisions - this one made more so given the many memorable moments we have had with Mauricio and his coaching staff - but we do so in the club's best interests."
Pochettino was appointed in May 2014 and led the club to the Champions League final last season, where they lost to Liverpool in Madrid.
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The Argentine's assistant Jesus Perez, and coaches Miguel d'Agostino and Antoni Jimenez have also left the club.
Tottenham said in a statement that they would provide an update on new coaching staff "in due course".
Former Southampton boss Pochettino guided Tottenham to the League Cup final in his first full season while two third-placed finishes sandwiched a runners-up spot in the Premier League in 2017.
As well as leading Spurs to a runners-up finish in last season's Champions League he also took them to fourth in the league, although they did only manage to win three of their final 12 league games.
He also had to contend with playing home games at Wembley for 18 months while the club's new ground was built and his impressive results despite this led to links with Real Madrid and Manchester United.
However, Spurs have failed to build on the promise of recent seasons this term. As well as their disappointing league form, they were knocked out of the League Cup by League Two side Colchester and hammered 7-2 at home by Bayern Munich in the Champions League.
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"Mauricio and his coaching staff will always be part of our history," added Levy.
"I have the utmost admiration for the manner in which he dealt with the difficult times away from a home ground whilst we built the new stadium and for the warmth and positivity he brought to us. I should like to thank him and his coaching staff for all they have contributed. They will always be welcome here.
"We have a talented squad. We need to re-energise and look to deliver a positive season for our supporters."
Analysis - right decision, wrong time?
BBC Radio 5 Live's football correspondent Ian Dennis:
There will be some supporters who are not surprised. They are without an away win in the league since January and they're on their worst run since George Graham was in charge in 2000-01. That is shocking form.
But what is a surprise will be the timing - why was the decision not made at the start of the international break? That, for me, is the interesting aspect.
I have always been of the belief that with the quality in this Tottenham side they, under Pochettino, would get back to the top four.
I know there are Tottenham fans who think this is the right decision, and there are some who think it is not the right decision, but I think we can all agree that it is the timing that is a surprise.
Pochettino at Spurs - highs and lows
- Pochettino was named Tottenham boss on 28 May, 2014 after taking Southampton to their best ever finish in the Premier League.
- After a fifth-placed finish in his first season at the club, he led them to third in 2015-16 - their highest final position in the Premier League.
- He became the first opposition manager to beat Pep Guardiola in England when Tottenham defeated Manchester City 2-0 in October 2016.
- Spurs continued to progress, finishing second and third respectively in the next two seasons.
- Led Tottenham to the last 16 of the Champions League in 2017-18 and was rewarded with a five-year contract in May 2018.
- Lost FA Cup semi-final to Manchester United in April 2018 - Tottenham's eighth successive defeat at that stage of the competition.
- However, Spurs reached the Champions League final for the first time the following season after a memorable comeback against Ajax.
- Lost 7-2 to Bayern Munich in the group stage of this season's Champions League.
- Departed Spurs on 19 November 2019 after just three Premier League wins all season.