i love football but would u really call it the worlds most popular sport? seems like the biggest countries in the world(population wise) are not that into it
though u can say its the most popular sport in europe
in the most populated country in the world (China), European football is very much watched.
NBA (basket-ball) as well.
But in Africa and south America, football/soccer is much more popular.
From everything I would say : 1. football/soccer 2. basket-ball