Edson Alvarez’s move to Fenerbahce is in major doubt, talkSPORT understands.
The West Ham midfielder had booked a private jet to fly to Istanbul on Tuesday to complete his switch.
However, Alvarez never boarded the flight and has now returned to Hammers training.
It leaves his transfer to Jose Mourinho’s side in jeopardy, with Porto and Borussia Dortmund joining the race for the Mexico international.
Alvarez was an unused substitute during the Hammers’ 3-0 defeat against Sunderland on Saturday.
Alvarez, who joined the Hammers in 2023 from Ajax for £35million, has 73 appearances under his belt for the club across two seasons.
Meanwhile, Fenerbahce are looking to secure a spot in the league phase of this season’s Champions League.
The Turkish side booked their spot in the play-off round thanks to a 6-4 aggregate victory over Feyenoord, who are managed by Dutch icon Robin van Persie, in the third qualifying round.
Mourinho had seen his side slip to a 2-1 defeat in the first leg but rebounded in impressive fashion with a 5-2 win at home in the second leg.
They will face Portuguese heavyweights Benfica in the play-off round, with the winner progressing to the Champions League proper.
As for the loser, they will drop into the league phase for the Europa League.
When was Fenerbahce last in the Champions League?
Should Fenerbahce get past Benfica, it would mark their first appearance in the Champions League proper since the 2008/09 campaign.
In previous years, the club was often knocked out in the third qualifying round or the play-offs.
But Mourinho, a two-time Champions League winner, is hoping to secure his side a return to Europe’s elite club competition after nearly two decades away.
The legendary manager had hoped the signing of Alvarez could go a long way towards doing just that.
Alvarez’s arrival would have been the latest in what has been a busy summer for the Turkish giants.
Sofyan Amrabat has joined from Fiorentina while tough-tackling centre-back Milan Skriniar arrived from Paris Saint-Germain.
Former Wolves captain Nelson Semedo was another who moved, as he linked up on a free transfer following the expiry of his contract with the Black Country side.
Fenerbahce also snapped up enigmatic striker Jhon Duran on loan from Saudi Pro League side Al Nassr.
However, the Colombian hasn’t quite settled into life under Mourinho.
What happened between Duran and Mourinho?
Murmurs of a rift between Duran and Mourinho emerged after the Portuguese boss suggested the striker failed to attend pre-season training in Portugal.
But Fenerbahce’s head of communications was quick to shut down any such talk
“The alleged statements attributed to our head coach Jose Mourinho in the foreign press regarding our player Jhon Duran are entirely false,” Alper Yemeniciler said.
“Our coach has not made any statements on this matter. Our player arrived in Portugal this [Wednesday] evening to join our team’s Algarve training camp.”
The first leg of Fenerbahce’s Champions League play-off against Benfica takes place on Wednesday with kickoff scheduled for 8pm.