Pompey’s pursuit of Michael Doyle is faltering after he pulled out of their trip to Portugal.
The experienced midfielder trained with the Blues on Thursday and had agreed to join the squad jetting off for Vale de Lobo on Friday afternoon.
However, the ex-Sheffield United man had a last-minute change of heart and pulled out.
It is understood the club are not presently in a position to offer him a deal, prompting Doyle to stay at home.
The 33-year-old had been interested in joining Pompey, while Cook had been chasing him for the majority of the summer.
It remains to be seen how the situation will develop, with the Blues not scheduled to return to England until Thursday afternoon.
However, should any of the club’s existing midfielders leave, it would open up the possibility for a concrete offer to be made to Doyle.
That is if both parties are still interested by that stage.
In the past week Pompey have managed to recruit fellow midfielder Adam Barton to Fratton Park following his release from Coventry City.
He joins Ben Close, Johnny Ertl, Nigel Atangana, Danny Hollands and James Dunne in what is already a clearly congested central area.
With Cook keen to operate a smaller squad than in previous seasons, it is obvious he is presently oversubscribed in current midfield numbers.
That is before taking into account the essential requirement of a right-back and at least one striker.
Pompey have so far brought in seven players during the close season, with 11 leaving.
Jed Wallace is the only departure to have attracted a fee, while a settlement was agreed with Craig Westcarr.