The midfielder missed Saturday's 2-1 win over Sunderland, and the Premier League side has confirmed
The 25-year-old Fellaini missed his club's 2-1 Premier League win over Sunderland over the weekend and subsequently underwent scans on his injured wrist with Belgium coach Marc Wilmots claiming the midfielder will require surgery at some stage.
Regardless, Fellaini is set to feature in his country's crucial World Cup qualifying doubleheader with Croatia on Friday and Wales on Tuesday.
"Marouane Fellaini has trained with Belgium wearing a protective cast on his injured wrist," an official Manchester United club statement read. "Although some reports suggest the midfielder faces an operation and a spell on the sidelines, the deadline-day arrival is due to play in a splint against Croatia and Wales in the World Cup qualifiers."
Belgium will travel to Zagreb to face Croatia, and a point will be enough to seal the nation's first World Cup berth since 2002.