Chelsea has a verbal agreement to acquire Chicago Fire and U.S. youth international goalkeeper Gabriel "Gaga" Slonina for a base fee of $10 million that could rise to $15m with add-ons, sources confirmed to ESPN.

Fabrizio Romano was first to report the news of the agreement, with The Athletic first to report the base fee.

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Slonina, 18, is headed to London to complete a medical exam and if it's successful will sign the deal, which will see him finish out the current MLS campaign on loan with the Fire and then head to Chelsea on Jan. 1.

Slonina has long been considered one of the jewels of the Fire's academy, and took over the starting goalkeeper spot with the first team last season as a 17-year-old. When Slonina made his professional debut Aug. 4, he became the youngest starting goalkeeper in league history at 17 years, 81 days.

Slonina has endured an up-and-down campaign in 2022, but following the 0-0 draw with Atlanta United on Saturday, he now has 14 shutouts in 34 career league appearances.

The Addison, Illinois-born Slonina has a Polish passport through his parents but declared earlier this year his intention to represent the U.S., for which he has appeared with multiple teams at the youth level.