Dominic Thiem, the 2020 US Open champion who retired this year, recently offered a fascinating glimpse into the teenage years of tennis's current superstars, Carlos Alcaraz and Jannik Sinner. While both have ascended to the pinnacle of the sport, Thiem revealed that his first impressions of them as 16-year-olds were strikingly different.

Thiem, who never faced either player in an official match, practiced with both during their formative years. On the BTA Podcast, he shared a telling comparison. He recalled hitting with a 16-year-old Alcaraz at the 2020 Rio Open, where Thiem was the top seed. "It was completely obvious that this guy was going to be amazing," Thiem said. "He was playing unbelievably fast, unbelievably heavy. I was in my peak back then and I had troubles with his ball."

His early assessment of Jannik Sinner, however, was more reserved. While he recognized Sinner's talent and believed he would have a strong career, Thiem admitted the Italian's potential for world-beating greatness wasn't as immediately apparent in their initial sessions. "With Jannik it was not the case," Thiem stated, highlighting how Alcaraz's explosive power and speed stood out even as a teenager.

This insight adds a compelling layer to one of tennis's best modern rivalries. Sinner himself has credited their frequent clashes with pushing his game to new heights. It's a reminder that a player's trajectory isn't always linear, and that greatness can announce itself in different ways. For fans and aspiring players alike, it's a testament to the unique blend of raw talent, relentless work ethic, and competitive fire required to reach the top of the game.