The matter is up to a court, more than likely even multiple courts if you release the game in multiple jurisdictions. 

In practice, either nothing happens, or you will receive a letter that will ask you to change the names. The letter will also threaten that you'll have to pay their lawyers' bills if you don't comply. The letter may also ask for a percentage of your proceeds so far, and it may also ask for a lump sum as well. You may receive multiple letters with some of them being scams and others being real.

If you ignore the letters and don't pay a lawyer to represent you in court, chances are very high that you will have to pay damages and cover some part of the other party's lawyer fees.

If you go after famous football/soccer players you are pretty much guaranteed to receive several such letters, because there are multiple organizations involved that take trademark protection very seriously.