https://fantasy.fifa.com/en
A few days ago FIFA's official World Cup Fantasy League opened. People can choose their initial fantasy lineups until the opening match. The overall winner gets a car, while individual round winners and runner-ups get memorabilia.
I played the previous iteration and it was quite fun. I created a league for fellow MZers. No prizes, just bragging rights. MZ League's code is DAYQL9QW if you're interested.
Before putting together a team read the rules of the game ;)