Nigeria's hopes of securing a fourth Africa Cup of Nations crown suffered a blow on Wednesday as influential midfielder Wilfred Ndidi was ruled out of the tournament.
The 27-year-old missed his team runaway Championship leaders Leicester City's 4-1 win over Huddersfield Town on Monday due to an unspecified injury.
Team spokesman Babafemi Raji said Ndidi has been replaced by midfielder Alhassan Yusuf, who has been in good form with Belgian champions Royal Antwerp.
Yusuf has yet to be capped by Nigeria, but was named in the 40-man provisional squad for the Cup of Nations.
Ndidi's Leicester City teammate Kelechi Iheanacho said he hopes to shake off a muscle injury to be available for the competition, which is being hosted by Ivory Coast and kicks off on January 13 in Abidjan.
The three-time African champions are training in the United Arab Emirates ahead of the tournament.
They have been drawn in Group A alongside Ivory Coast, Guinea Bissau and Equatorial Guinea.
They face Equatorial Guinea in their opening match on January 14.