Portsmouth look to have missed out on signing Charlton centre half Souleymane Diawara because of a FIFA rule banning players turning out for more than two clubs in a year.
Pompey boss Harry Redknapp wanted to bring Diawara to Fratton Park on a loan deal in a swap for out-of-favour Andy O'Brien - having bought full back Djimi Traore from Charlton for £1million only last week.
But FIFA's rules state no player may play for three clubs in a year starting July 1 - and it has been discovered that the Senegalese player was in French club Sochaux's team before his £3.7million debut for Charlton against Chelsea on September 9.
Pompey could appeal but now Charlton boss Alan Pardew is saying he is happy to keep Diawara - who could now turn out against Redknapp's team at Fratton Park on Saturday.
The Portsmouth boss will set his sights on another central defender and could take 21-year-old Frenchman Younes Kaboul from Auxerre either on loan or for a fee.
And new owner Alexandre Gaydamak has promised Redknapp full backing, saying: 'Transfer decisions are Harry's and only Harry's. That is clear.
Gaydamak, who has again denied reports he is thinking of selling the club just a few months after buying out former chairman Milan Mandaric, added: 'I have a list of players he requested and we will do our best to bring in the players he's asked for.'
Gaydamak, 30, has also talked to Pompey supporters at a special meeting about moving the club out of Fratton Park within three years.
He said: 'We have studied two options over the past seven months and one is improving the current site, but that would be only an upgraded refurbishment.
'It is an emotional subject because the club has been here for 110 years but, to be honest, I am in favour of a relocation. Three years ? It could be done. After all, Arsenal managed theirs in 28 months.'
Pompey are believed to be looking at a site for redevelopment at nearby Cosham.