Cameroon enter their most important match of the year trailing by two goals and with a new coach, while Nigeria will be without their captain for this weekend's decisive final round of qualifying games for the 2013 African Cup of Nations.
Morocco and defending champion Zambia also are under pressure as qualifying reaches its climax with 15 second-leg matches to decide which teams join host South Africa at the continental championship early next year.
Four-time African Cup winners Cameroon - under Jean-Paul Akono for the first time - trail Cape Verde 2-0 on aggregate ahead of their home leg on Sunday. Nigeria host Liberia on Saturday without injured skipper Joseph Yobo and with that tie finely balanced at 2-2.
Morocco must overturn a 2-0 deficit at home against Mozambique.
Top-ranked African team Ivory Coast travel to Senegal with a 4-2 lead and for a contest that will see one of the two powerhouses miss out in the final act of a scrambled qualifying process that was squashed into nine months and began before the last tournament ended because of the Cup's shift to odd years.
Ghana leads Malawi 2-0, Mali has a 3-0 first-leg lead over Botswana, and Algeria takes a narrow 1-0 advantage back home in its tie against Libya.
Cape Verde's shocking victory over Cameroon on the Atlantic Ocean island last month underlined the recent rise of Africa's lesser-known teams at the expense of their higher-ranked rivals.
Central African Republic, who, like Cape Verde, have never played at a major tournament, lead Burkina Faso 1-0. Despite all of their problems resulting from a match-fixing scandal that implicated national team players, Zimbabwe have a 3-1 advantage over Angola.
Zambia, just eight months after their emotional triumph at the last African Cup in Gabon, have a narrow 1-0 lead ahead of their game in Uganda.
Reeling from unrest in their camp, Cameroon lost in Cape Verde to leave them in danger of missing out on a second straight Cup of Nations. That would be an almost unthinkable failure for the 2000 and 2002 winners, who fired Frenchman Denis Lavagne as coach, brought back Olympic title-winning coach Akono and convinced leading striker Samuel Eto'o to end his international exile ahead of the crucial match.
Akono said his first priority was to restore a flagging team spirit and put his players "back on their feet" before the game in Yaounde, where the returning Eto'o is likely to be Cameroon's linchpin.
Defender Yobo was in tears, the Nigerian Football Federation said, when he was forced to pull out of the home game against Liberia with a knee injury. Like Cameroon, Nigeria would be excluded from successive African Cups if they can't get past a dangerous Liberia in Calabar.
"Come Saturday, we will give the nation a sweet victory and qualify for the Nations Cup in South Africa," Nigeria coach Stephen Keshi said, predicting the victory that his job likely depends on.
Belgium's Eric Gerets was fired following Morocco's 2-0 first-leg defeat in Mozambique. He was replaced by Rachid Taoussi who, like Akono, has just one game to turn his team around. Taoussi said his players would work like "a commando unit" to ensure qualification.
"Everyone will know his mission," he said. "The players all know that with these 90 minutes the team can make history. It's a new generation and a new chance for the national team."
Zambia's French coach Herve Renard was reportedly ready to revive his lucky white shirt that was a feature in Zambia's run to their greatest footballing achievement, when they beat star-studded Ivory Coast to win the title in February. But boosted by their best qualifying campaign in years, Zambia's opponent Uganda have sights on their first African Cup appearance since 1978, when they lost in the final to hosts Ghana.
Ghana should qualify ahead of Malawi despite the loss of Udinese midfielder Emmanuel Agyemang Badu with injury.
In maybe the most intriguing development, Zimbabwe lead 2010 African Cup host Angola 3-1 and could qualify for the Cup of Nations for just the third time despite the significant burden of a damaging investigation that alleged national team games were fixed by officials, coaches and players for money.
Zimbabwe's football association this week delayed releasing the findings of a judge-led investigation until next week to ensure its players retained their focus for Angola on Sunday.
Congo are almost certain of their place in South Africa after beating Equatorial Guinea 4-0 last month for the most dominant first-leg result. In other ties, Tunisia and Sierra Leone are level at 2-2 Sudan leads Ethiopia 5-3 and Togo and Gabon's tie sits at 1-1.
Next year's African Cup begins on January 19, with the final on February 10.