Just in theory, if the match was in Africa and most of the players were black, and there was one white player - if the white player is called "the white one", would that be considered racist?
I would honestly say yes, that's also a form of racism.
But I'm sure you know we should consider additional key contexts here. When "white" is being used, it's less used as a mocking, but rather, just a description of skin color. When "black" is used, not only it is a description of skin color, but even more so and it is universally known that it is often being used to downgrade people, mocking them by referring it to you know "something that is just not nice at all".... basically "white" is not really insulting (some people would find it insulting yes), while "black" is almost always, usually insulting.
If we only could stop labelling each other with skin colors... for god sake, skin color doesn't define us. There are so many variations. really... I mean even people with basic white colour can have reddish white, yellowish white or darken white, and even people with basic black color skins can have lighter brown or yellowish brown color. So what do we call those in between then? Geez. I never get this racist thing labelling people with skin color. Experienced it plenty myself towards me and others, and it stings alright. I never understand why they need to say that. Says a lot about themselves as a person I guess. Can't blame society since there are people who refuse to follow the common racist culture in the same society.
If we can only be more sensible and more civilized to use professions instead or maybe just use our clothes as a point of references (eg. the guy wearing red shirt, etc) if we don't know their names, gender or professions... that would be great.