Angola and Nigeria could be the first two sides to clinch places at the 2008 African Cup of Nations finals if results go in their favour.
Both sides need to win their weekend qualifiers and hope that their closest challengers are beaten if they are to reach the finals in Ghana next year.
The two are among four sides with 100 percent records halfway through the qualifying competition but they are the only teams with a chance this weekend of making mathematically certain of their progress to the 2008 finals in Ghana.
Nigeria can qualify at the head of Group Three if they beat Uganda away in Kampala on Saturday and Lesotho fail to beat Niger in Niamey in the group's other game on Sunday.
The Super Eagles' quest received a major boost with the belated arrival of Newcastle United striker Obafemi Martins at their training camp on Tuesday.
He missed a warm-up against Kenya at the weekend and was accused by officials of deserting the team but he told reporters he had had "passport problems".
His arrival comes as some relief to new coach Berti Vogts after Lille striker Peter Odemwingie withdrew because of injury.
World Cup finalists Angola will qualify from Group Six if they beat Eritrea away in Asmara on Saturday and Kenya lose in Swaziland the next day. Angola hammered Eritrea 6-1 in Luanda in March and with the qualifying competition's top scorer Flavio and Benfica's Mantorras in the squad they will be looking for a similar goal spree.
Nigeria and Angola share 100 percent records with the Ivory Coast and Cameroon, who can move to within one point of qualification if they win on Sunday.
The Ivorians will turn to the goal scoring acumen of Didier Drogba to extend their Group One lead when they host Madagascar in Bouake on Sunday.
In a symbolic gesture to reinforce the country's fragile peace process, the match has been shifted to the former rebel capital in the north.
African Footballer of the Year Drogba is likely to be joined in attack by Chelsea team mate Salomon Kalou, set to earn his third cap for the country.
Samuel Eto'o takes time off from the Spanish league title race to lead Cameroon against Liberia in Monrovia in Group Five.
Home wins for the likes of Morocco, South Africa and Tunisia will also take them a step closer to securing a berth in the finals.
Algeria, Egypt, Senegal and Togo also need to win away from home to keep up their front-runner roles.
A total of 22 games in 12 groups are being played over the weekend in the quest for 15 finalists to join hosts Ghana in next January's tournament.