Tottenham Hotspur sacked manager Mauricio Pochettino late Tuesday following a miserable start to the season with Jose Mourinho hotly tipped to replace the Argentine.
The BBC and Sky Sports reported that Spurs and Mourinho, who was sacked by Manchester United 11 months ago, were holding talks late into Tuesday night with both sides believing a deal was close.
The Portuguese former Chelsea boss could be announced as manager as early as Wednesday, the reports said.
He would then be unveiled at a press conference Thursday and take charge for the home game against West Ham on Saturday lunchtime, they added.
Tottenham are languishing 14th in England's Premier League after picking up just three wins from their opening 12 games, and were eliminated from the League Cup in September by fourth-tier Colchester United.
"The club can today announce that Mauricio Pochettino and his coaching staff Jesus Perez, Miguel D'Agostino and Antoni Jimenez have been relieved of their duties," Tottenham said in a statement.
Pochettino, 47, transformed Spurs' fortunes since arriving from Southampton in 2014, despite failing to win a trophy.
During his five full seasons in charge, Tottenham qualified for the Champions League four times, culminating in a dramatic run to the club's first ever European Cup final in June, which they lost 2-0 to Liverpool in Madrid.
However, domestic results had been on the decline since February, with Spurs clinging on to a top-four finish last season despite winning just three of their final 12 league games.
That form has continued at the start of this season and Pochettino leaves the club 11 points outside the Premier League top four, 20 behind leaders Liverpool and just six points above the relegation zone.
Spurs suffered an embarrassing 7-2 thrashing at home by Bayern Munich in the Champions League in September, but are well-placed to reach the last 16 behind the German giants in Group B.
"We were extremely reluctant to make this change and it is not a decision the board has taken lightly, nor in haste," said Tottenham chairman Daniel Levy.
"Regrettably domestic results at the end of last season and beginning of this season have been extremely disappointing.
"It falls to 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."
The job done by Pochettino was all the more remarkable given the tight budget he was afforded by Levy for transfers and wages in comparison to Tottenham's Premier League rivals, as the club built a new stadium at a cost of over £1 billion ($1.3 billion).
Instead, much of Pochettino's success came from nurturing a squad of young players into household names such as Harry Kane, Dele Alli and Christian Eriksen.
"I can't thank this man enough," Alli tweeted alongside a picture of Pochettino with the England international.
"He's taught me so much and I'm so grateful for everything he's done for me. Good luck and hope to see you again my friend."
Spurs were forced to play at temporary home Wembley for the entirety of the 2017/18 campaign and most of last season before moving into their new 62,000 capacity ground in April.
After 18 months without signing a single player, Levy finally loosened the purse strings to buy Tanguy Ndombele for a club record £63 million in July and added Giovani Lo Celso on loan and Ryan Sessegnon in the summer transfer window.
However, injuries have prevented that trio making an instant impact, while Pochettino bemoaned the disruptive effect of Eriksen, Toby Alderweireld and Jan Vertonghen all entering the final year of their contracts.
"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," added Levy.
"We have a talented squad. We need to re-energise and look to deliver a positive season for our supporters."
However, the Tottenham Hotspur Supporters' Trust questioned Levy's role in the diminishing results on the pitch.
"Is the manager solely accountable? How much has the board's line on wages and transfers contributed to player unrest and disaffection?" THST said in a statement.
"Poch gave us many of our best moments as supporters, made Tottenham Hotspur a force to be reckoned with again, and forged a strong link with the fans. We will never forget the joy he brought us."