I call them a man u fan.
A fan, sometimes also called aficionado or supporter, is a person who supports with a liking and enthusiasm for something, such as a band, a sports team or entertainer. Fans of a particular thing or person constitute its fanbase or fandom. They may show their enthusiasm by being a member of a fan club, holding fan conventions, creating fanzines, writing fan mail, or by promoting the object of their interest and attention. Some fans even take it as far as impersonating their idol or go into a state of insanity by believing they are the character the person is obsessed with.
It is not the same with every person.
I would call them a "Fanatic" or "Super Fan"
Sports fan = Sportsfreund (male) Sports fan = Sportsfreundin (female)
Technically a fan would be a sports' fan but the plural noun is used as an adjunct here, so sports fan is also correct.
Sports Fan Radio Network ended in 2001.
Sports Fan Radio Network was created in 1996.
Tiger Woods grew up in the bay area of California and has said before that he is a fan of the Oakland Raiders. As for College Football, he supports Stanford.
A sports fan. Someone who likes sports.