Why only Canon lenses used for sport photography these days?

Why is it when there is a sports event on box, there only seems
!! to be Canon lenses being used. Has Nikon given up the chase or are Canon simply a better telephoto in the 300 to 800mm market.
I do not really have a preference but just simply like to know why as there used to be Nikon back in the older film days and not many Canons?

I do not really have a preference but just simply like to know why as there used to be Nikon back in the older film days and not many Canons?