Tottenham Hotspur and Sporting CP have hit a wall in talks over right-back Pedro Porro, 90min understands.
The 23-year-old Spanish international had hoped he would be in London on Monday to complete a medical ahead of his move, but he yet to get the green light.
Porro agreed personal terms with Tottenham earlier in the week and played what he hoped would be his final game for Sporting on Saturday evening as they lost the League Cup final to Porto, appearing to bid farewell to supporters after the final whistle.
Sporting were confident a deal would be done, hence their agreement with Barcelona to land Hector Bellerin as his replacement - as confirmed by 90min on Sunday.
Tottenham believed they had an agreement to pay Porro's release clause of €45m in instalments, but Sporting insist that was never the case.
Now, as it stands, the deal is off but sources from both sides have told 90min that they still expect talks to continue over the remaining 48 hours of the transfer window.
Tottenham have also seen their enquiry for Bayer Leverkusen defender Pedro Hincapie rejected by the Bundesliga outfit.