By Steve Vickers BBC Sport

Caf will use a complex formula to decide the best runners-up

The 12 group winners in the first group phase and the eight best runners-up will advance to the second stage.

But a fair amount of mathematics will be required to discover those best runners-up.

One of the 12 groups has only three teams, and Caf wants to give the runners-up in that group a fair chance of qualifying.

So rather than simply looking at points gained and goal difference to determine the best second-placed teams, a re-calculation will take place.

The runners-up in groups 8 and 11, which have three teams will have their statistics unchanged.

But in the other groups, the points and goal difference that the second-placed teams had against the fourth-placed team will be erased.

These new totals will then be used to determine the eight best runners-up, using points gained and then goal difference, then goals scored.

Caf says that a play-off match will take place in November should there be a tie for the eighth best runners-up spot.

Second stage

The 20 teams that qualify for the second group stage will be drawn in five groups of four teams.

The group winners qualify for the 2010 World Cup, but should hosts South Africa win a group, there will be a recalculation to determine the team that goes to the World Cup.

All results against South Africa would be erased and a new table calculated.

The first three teams in each group will qualify for the 2010 Nations Cup.

If Angola reach the second group stage, the three teams drawn in their group will automatically qualify for the Nations Cup.