Portsmouth hope to have Manuel Fernandes fit in time for the home game against Bolton on 25 September.
Fernandes could become the club's record signing
The 20-year-old midfielder has a groin injury which twice blocked a permanent move to the Fratton Park club.
Fernandes was eventually signed on loan from Benfica with a view to a club record £7m move.
Pompey physio Gary Sadler said: "Hopefully, without any setbacks, he will be involved with the first team by the end of the month."
Meanwhile, Portsmouth right-back Glen Johnson has returned to Chelsea - but only for treatment to his injured ankle.
He is also aiming to be fit for the home game against Bolton.