Praise be to Allah.
We put this question to Shaykh Muhammad ibn Saalih al-‘Uthaymeen, may Allaah preserve him, who answered as follows:
There are many wrong things involved in football, such as showing the ‘awrah (parts of the body that should be covered) and swearing, etc. Taking part in these things is haraam. So let them look for something else, and Allaah will provide for them.