From the U.S. youth movement to Messi's Argentina farewell and AFCON qualifying beginning in Africa, there's a lot happening in international soccer over the next 15 days.

For the U.S., under returning manager Mauricio Pochettino, it's clear that one of the primary goals is to test out the next generation of talent. Of the 28 called up, a total of 13 could claim a national team debut, and eight of those 13 are still teenagers, which includes 16-year-old phenom Cavan Sullivan. With key figures like Christian Pulisic, Folarin Balogun and Weston McKennie being rested, Pochettino's fall roster doesn't have a single player over the age of 30.

As for Mexico, new manager Rafael Marquez is taking a different route, focusing on bringing back a strong core of veterans. Highlighted by teenage rising star Gilberto Mora, Marquez's roster has 11 players who are 23 and younger. Expect fireworks when the rival nations face off on Oct. 3.

When Lionel Messi announced his retirement from international soccer at the end of August, Argentina organized a farewell game. Messi will don the shirt for the last time against Benin in Buenos Aires on Oct. 6 at River Plate's ground.