Porto are unhappy with the way Andre Villas-Boas walked out to take over at Chelsea last week, and are insisting that the Stamford Bridge club must pay the full get-out clause for any players he wants to take with him.
Porto's preparations for a new campaign under Villas-Boas had included the completion of four signings in the close season, supervised by a manager they did not expect to leave. Porto are indignant that Villas-Boas let them undertake this business, with suspicions in Portugal that his discussions with Chelsea had been ongoing for six weeks, and are unlikely to allow any room for manoeuvre in summer business between the two clubs.
Striker Radamel Falcao's get-out clause gives a figure of €30m (£26.7m) while the figure for midfielder Joao Moutinho is understood to be around €40m (£35.7m), which makes adding him to the Chelsea shopping list seemingly prohibitive. Real Madrid have also been interested in Falcao though discussions about a move to join Villas-Boas' former mentor Jose Mourinho have been dragging on and Chelsea now appear to be favourites.
Chelsea paid Porto the full €15m (£13.3m) to release Villas-Boas from his contract.
Villas-Boas has also been ruffling feathers in the Netherlands, after his decision to cancel next week's friendly at Vitesse Arnhem at short notice. Chelsea's players return for pre-season training next Monday and were due to play Vitesse just five days later. However, Villas-Boas has decreed this is too soon to be playing a friendly, and Chelsea yesterday announced that the game had been cancelled.
The Vitesse general director Paul van der Kraan yesterday described Chelsea's cancellation as "a major annoyance" as the Dutch club were anticipating a crowd of 12,000. They had included the prestigious friendly as a free ticket to anyone buying a season ticket, and now are facing giving out a €25 (£22) credit note to use in the club shop to those who are affected, as well as refunds to those fans who had bought tickets.
Chelsea yesterday said sorry for the inconvenience, saying in a statement: "The club would like to apologise to fans that were planning on attending the match in Holland next month. A full refund will be given to those Chelsea supporters who have bought match tickets, and the club will be in contact with those fans over the coming days to arrange this. Chelsea also extends an apology to Vitesse Arnhem for this cancellation."
Villas-Boas's first game in charge will now be a friendly at Portsmouth on 16 July before Chelsea head off for a four-game tour of the Far East.
The 33-year-old manager is to be unveiled to the media this week, after putting the finishing touches to his personnel. Villas-Boas has already sacked three backroom staff, just five days after taking charge: the assistant first-team coach Paul Clement, the medical director Bryan English and the fitness coach Glen Driscoll have all been put on gardening leave while compensation packages are agreed.
There is also doubt about the future of Chelsea's French goalkeeping coach Christophe Lollichon, who joined Chelsea in 2007 from Rennes, where he worked with Petr Cech.
Meanwhile, the former Chelsea manager Avram Grant yesterday claimed Villas-Boas will be allowed the freedom to work without interference from the club's owner.
Grant said: "It is very easy to work under Roman Abramovich. I have read people in the paper saying that he interferes, but it is not true – he gives you everything you want and you are even sometimes afraid to say something, because you know the day after you will have it.
"He is a perfectionist. He wants to achieve the best and he will give you everything to achieve the best, so he wants the results – but he's easy to work with."