The Olympic men's soccer group stage kicked off yesterday — but, per Yahoo Sports, don't expect to see the world's top players taking the pitch.

Kylian Mbappé really wanted to play at the Paris Olympics. Lionel Messi reportedly did too. But neither will, because they, like most men's soccer stars, are victims of an age-old power struggle domineered by the sport's global governing body, FIFA.

The struggle is the reason organizers impose two key restrictions on each men's Olympic roster:

1. All but three players must be 23 years old or younger.

2. No matter the player's age, his professional club isn't required to grant him permission to play at the tournament.

The second rule spoiled Mbappé's dream. "I've always said that the Games in Paris are special, and I wanted to be there," the native Parisian said in March. But Real Madrid refused to release him.

Dozens of other clubs have also declined to grant necessary permissions. And so, of the world's top 100 players, only two — Argentina's Julián Álvarez and Morocco’s Achraf Hakimi — will be present.

The rules make Olympic men's soccer something of a junior varsity competition. And they're in place because FIFA doesn't want the Games — or any other soccer tournament — to rival its World Cup.

Good news for Team USA? The upside of the Olympic roster limitations is that they can be an equalizing force, one that could give the U.S. hope of medaling.

The USMNT, of course, has never been past the quarterfinals of a modern World Cup; it can't measure up to France, Spain or Argentina. But its JV team could compete with other JV squads around the world.

The Americans will be expected to advance from the group stage and could contend for a medal in their first Olympics appearance since 2008.