The forward, who has netted 14 goals in the Greek Super League and impressed in the Champions League this season, is set to join the London side for a club-record fee.
The Cottagers are currently struggling at the wrong end of the Premier League table and are prepared to equal the club-record fee they paid for Steve Marlet in 2001.
The 25-year-old Greece international leads the scoring charts in Greece with 14 goals and is enjoying an impressive Champions League campaign, scoring a hat trick against Anderlecht as Olympiakos qualified from the group stage to set up a last-16 tie against Manchester United.
Fulham appears to have won the battle to maintain the services of Tottenham target Dimitar Berbatov but possesses one of the weakest attacks in the division and is in need of reinforcements, particularly after allowing Bryan Ruiz to leave for PSV earlier this month.
In the back, Rene Meulensteen has been vocal in his desire to sign West Ham's Ravel Morrison and Swansea left back Neil Taylor.