The Hammers thought they had landed a replacement after agreeing a deal to sign Inter Milan defender Davide Santon on loan, but the move fell through after the former Newcastle man failed a medical. Bids for Norwich defenders Robbie Brady and Marton Olsson also failed.
Reports from Greece claim Masuaku boarded a morning flight to London with his agent Panagiotis Galarioti. The report in www.gazzetta.gr claims West Ham have bid 10 million euros and he will face a medical this weekend.
Masuaku has impressed since joining Olympiakos from Valenciennes two seasons ago. The 22-year-old helped them win the Greek title in the last two seasons and has played in the Champions League. Olympiakos face a battle to keep hold of their left back and West Ham are said to be ready to test their resolve with a £6 million bid.