Concerns surrounding captain Asamoah Gyan's fitness could scupper Ghana's bid to reach a sixth successive African Nations Cup semi-final when they take on the Democratic Republic of Congo in the last eight in Oyem on Sunday.
Gyan's fitness woes have clouded Ghana's preparations for the encounter against a fast-emerging Congolese side, who finished top of their first-round group. It was the same group from which holders Ivory Coast were eliminated.
"Two giants, Ivory Coast and Algeria, are out of the way so it's a good wake-up call to all the people that think they are a big team and that it's enough," said Ghana coach Avram Grant.
"It's not enough. You need to prove it on the pitch."
The last quarter-final pits Egypt and Morocco, who are both enjoying a revival in their fortunes in Gabon.
Egypt, despite a record seven titles, did not qualify for the last three Nations Cup finals while Morocco got past the group stage for the first time since 2004.
Difficult pitch conditions in Port Gentil await both teams on Sunday.
"It is always necessary to have a remarkable capacity of adaptation," Morocco coach Herve Renard told reporters.
The winner of the Egypt v Morocco clash will take on Burkina Faso, who beat Tunisia 2-0 on Saturday.
Cameroon, who eliminated Senegal on penalties, will take on either DR Congo or Ghana on Thursday in Franceville.