I'm pretty sure like 1% of Americans would say Baseball is the world's biggest sport. Considering that it's only really big in America, it's a pretty unlikley answer. You're making Americans out to be more stupid than they are (yes, Ive got the jokes too, but Im one infraction too many as it is).
Regardless, right this second, in total across the world, football is the biggest sport in the world. It might not be the most popular in YOUR country, but if you have any sort of cultural awareness you will know how big it is. I dont watch handegg because it's one guy throwing a ball to another, then he gets tackled and the whole thing restarts. That doesnt mean that Im not aware of how popular the NFL is.
EDIT: Grapple, rephrase to just "soccer" in general. English football seems like you're referring to the premiership alone.