Don't be surprised if U.S. Soccer is a force to be reckoned with in a decade ... 'cause Landon Donovan tells TMZ Sports America hosting World Cup games will inspire MILLIONS of kids to pursue the sport -- and he's living proof of it!!

We spoke with the legendary forward and midfielder ahead of the tournament ... and asked about the impact the next few weeks will have on the country, which has historically struggled to keep up with the rest of the world when it comes to futbol.

Donovan was certain it'll be felt ... and pointed to the time he was 12 years old and fell in love with the sport that ultimately became his career.

"So in '94, I went to my first World Cup game," Donovan said during an honorary shift at Raising Cane's in Inglewood. "And I didn't know about soccer at all outside of just playing out in the park."

He still remembers watching Argentina and Romania duke it out at the Rose Bowl ... and how it opened his eyes to a "bigger world that I didn't know existed."

Donovan said kids will watch Weston McKennie and Christian Pulisic and want to walk in their footsteps ... and that would happen even if the World Cup was going down overseas -- so the fact it's on U.S. soil will only amplify the impact.

Speaking of CP, we asked Donovan if there's a chance the 27-year-old goes down as the greatest to ever suit up for the Red, White and Blue ... and he's got an interesting perspective on the debate.

The FIFA World Cup™ 2026 kicks off on Thursday ... and FOX One will be streaming all 104 matches from June 11 to July 19, so tune in and see how the good ol' US of A does this time around!!