But the Nigeria squad was boosted with the arrival of Chelsea star John Mikel Obi, who trained with the rest of the team.
NFF Acting Chief Media Officer Robinson Okosun explained that Etuhu picked up the injury in Fulham's last Premier League match.
“Etuhu informed us about the injury, but we asked him to report here so our doctors could ascertain the severity of the injury.
"They confirmed the situation, but he will remain to support his team mates on Sunday.”
With Mikel's arrival, captain Joseph Yobo is the only player still being expected in camp.
The defender was given permission to finalise his move to Turkish giants Fenerbahce.
Yobo will join the team on Thursday morning.