Top-flight sportsmen who are avowed fans of rival teams?

I’ve never really gotten into sports fandom, hence I’ve never been a fan of any team, but people who are fans tend to take it quite seriously. Professional sportsemen are generally expected to shop around and take the best deal. Any examples of cases where those worls collided. (e.g a footballer working for and doing his best for Arsenal whilst still maintaining Tottenham fandom, possibly even still going to watch Spurs games when Arsenal aren’t playing/he isn’t picked)?

If the answer’s yes, any major cases where the player knocks out/denies promotion/relegates his fandom team whilst playing against them?

Apparently a number of Everton fans went on to play for Liverpool, Adam Lallana being the latest. Jamie Carragher, Robbie Fowler, and Michael Owen are also on that list.