Spain's Usman Garuba, the No. 15 basketball prospect in the ESPN Top 100, has submitted paperwork to the league office to make himself eligible for the 2021 NBA draft, a source told ESPN on Thursday.

Garuba, 19, is in the midst of a productive season competing at the highest levels of international basketball, already taking part in 79 games across the Euroleague, Spanish ACB and domestic Cup competitions.

He is averaging 5.6 points and 5.3 rebounds in 19 minutes per game in the ACB for Real Madrid, who just completed the regular season at 34-2 to claim the No. 1 seed in the playoffs, starting next week. The team lost in the Euroleague quarterfinals to reigning champions Anadolu Efes in a five-game series that saw Garuba play some of his best basketball of the season, including a career-high 24-point, 12-rebound performance in a crucial Game 4 victory.

That playoff series helped cement his status as the Euroleague's best player under the age of 22, being awarded the competition's Rising Star trophy in mid-May. He was also named the "Best Young Player" of the 2020-2021 ACB season in late April.

Garuba is arguably the most versatile defensive prospect in the 2021 NBA draft, as he already has considerable experience guarding some of the most formidable players in the international game, be it smaller point guards, playmaking wings or traditional big men.

While slightly undersized for a big man at 6-foot-8 and 230 pounds, Garuba has a reported 7-foot-3 wingspan that allows him to play much bigger than his height, complementing his outstanding intensity level and instincts. A strong passer and developing 3-point shooter, Garuba has drawn comparisons from NBA scouts to the likes of OG Anunoby and P.J. Washington with his style of play.

Born in Spain to parents from Nigeria, Garuba has been a stalwart for the Spanish national team level since he was a 14-year-old, competing at the U16 and U18 European Championships and winning gold medals at both events. He helped Real Madrid win the prestigious Euroleague Basketball Adidas Next Generation Tournament in 2019, a competition for Europe's top junior club programs.

Garuba's season will be finished no later than the middle of June, at which point he'll likely head to the United States for private team workouts and interviews in hopes of cementing his status as a lottery pick. The NBA draft lottery will be held June 22. The draft will be held just over a month later on July 29.

Jonathan Givony is an NBA draft expert and the founder and co-owner of DraftExpress.com, a private scouting and analytics service utilized by NBA, NCAA and International teams.