Manchester United centre-back Rio Ferdinand has expressed gratitude to Fulham after the London club signed the star player from his side's forthcoming Champions League opponents Olympiakos.

Fulham, managed by former United coach Rene Meulensteen, completed a move for Greece international striker Konstantinos Mitroglou on Friday.

Mitroglou is the top scorer in this season's Greek Super League, with 14 goals, and Ferdinand is relieved that he will not come up against the 25-year-old when United tackle Olympiakos in the Champions League last 16.

"Fulham just signed our next opponents star man," Ferdinand wrote on Twitter. "good work Rene!!"