Senegal are hoping coach Aliou Cisse will clamber off his sick bed to lead the team against England.
Cisse has been ill the last two days, and failed to take training on Friday as a result.
His assistant Regis Bogaert faced the press ahead of the World Cup last-16 clash but remains confident Cisse will be on the bench at Al Bayt Stadium on Sunday.
He said: "He's been sick for a couple of days now and he let us [the staff] take charge of training yesterday, with his instructions.
"We are sure that at 10 pm tomorrow, he will be there."
Senegal are African champions and edged out Ecuador to secure qualification from Group A and underline their growing reputation on the world stage.
Bogaert added: "We know Senegal can beat England. We need to focus on our African identity and be positive with the experiences we are having at the moment.
"Since the last World Cup, we have matured. We can beat anybody and when we go on the pitch we need to be convinced of that.
"Our objective is to get through. We're not too excited and trying to ensure we stay as calm as possible."
Senegal's finest moment at the World Cup came 20 years ago with a 1-0 win over France in the opening game of the 2002 tournament in Japan and South Korea.
Asked how beating England would compare, Bogaert said: "It would be a tremendous achievement, although I am not sure how it would compare to the win in 2002.
"For the players, it would show them that we are capable of playing one of the top five sides in the world. If we can beat a team like that it sends a very strong message of the progress we have made."
Bogaert believes set pieces could be key on Sunday and is hoping it is an area they can use to spring a major surprise.
"We have studied the different types of set plays they employ and we will try to adopt the best possible strategy," he said.
"We have identified some things and set-pieces can be decisive. We hope to take advantage of them and cause problems for our opponent."