Manchester United's big-money signing Marouane Fellaini faces several weeks on the sidelines after having an operation on his wrist.

The club said yesterday that Fellaini had undergone surgery and said that manager David Moyes would provide more details on his anticipated return to competitive action later. The injury means the mop-haired Belgium midfielder could miss both legs of United's Champions League last-16 clash with Olympiakos Piraeus in February and March.

Fellaini has struggled this season to replicate the form that persuaded United to pay Everton 24 million pounds (US$39.25 million) for him in September. He has yet to score a goal in 11 appearances for the Premier League champion.