Marcelo Mattos's agent has confirmed that they are considering offers from a number of English teams - including Portsmouth.
The Brazilian midfielder is very highly-rated after an outstanding campaign for Panathinaikos.
Pompey made their move last month after it became known that Mattos has a release clause in his contract of £5.9million.
Portsmouth have attempted to play down talk of a bid but now the player's representative Pini Zahavi has now confirmed their interest.
Zahavi has revealed that Pompey are one of three Premier League clubs trying to sign the 24-year-old.
"At this moment we are considering offers from English clubs, one is from Portsmouth and two more," Zahavi told Greek newspaper Goal.
"But it is possible for Mattos to stay at Panathinaikos, the player is very happy with the working conditions there and he loves the fans," he continued.
"He is also very satisfied with the attitude of the people at the club, we will have to wait a few weeks as the transfer market does not officially open until July."