As I already explained last November, Spain will lose their place at the top of the ranking. It will happen either on March 31st or on April 28th, but we'll know exactly on March 3rd.
Brazil need to better against the Republic of Ireland than Spain do against France.
Here are the possible outcomes for Spain and Brazil, depending on their results on March 3rd (and 2nd):
Spain (L - 1563, D - 1576, W - 1602)
Brazil (L - 1559, D - 1569, W - 1589)
If Spain lose against France, Brazil need to get at least a draw against the Republic of Ireland.
If Spain get a point against France, Brazil need three in their match.
If Spain defeat France, they will keep their spot at the top of the rankings.
Since Brazil and Spain don't have other matches before March 31st, we'll know the outcome on March 3rd.
Even if Spain keep their top spot, Brazil will surely overtake them on April 28th.
Spain's total in April with a win against France: 1565 points.
Brazil's total in April with a loss against the Republic of Ireland: 1579 points.
Will that make Brazil a World Cup favorite for Iker Casillas?