Jannik Sinner and Carlos Alcaraz reflected on their very first meeting at an ATP Challenger Tour event when they were teenagers.

The young stars have become two of the best players in the world, sharing four Grand Slam titles in 2024. But their rivalry began in the first round of the Alicante Challenger five years ago.

Sinner has now admitted he had “no idea” who the Spaniard was, but he was eager to get to know him after being beaten by him and meeting his younger rival in the locker room.

Sinner and Alcaraz formed one of the most exciting rivalries in tennis. They have already met 10 times, with the world number 3 leading their head-to-head with six wins and four losses.

Both have reached the top of the rankings and won multiple Grand Slam titles – Alcaraz has four and Sinner claimed her first two this year. They faced each other in Majors, Masters tournaments and in the final.

But their rivalry began on a modest clay court in Villena, where they faced off in the first round of the Alicante Challenger in April 2019. Both had received wildcards into the main draw.

Alcaraz was only 15 years old and Sinner 17 years old. Playing on outdoor clay at the Juan Carlos Ferrero Academy, the Spaniard needed an hour and 50 minutes to seal a 6-2 3-6 6-3 victory.

It was the first of a long series of meetings. More than five years later, while both competing in the season-ending championships in Turin, the rivals sat down to share their first impressions of each other.

“I saw the draw and I saw Carlos AlcarazI had no idea who he was,” Sinner told CNN. “I saw his age and I was like wow, he’s playing a Challenger, that’s incredible. I was immediately impressed .

Although the world number 1 had never heard of his opponent, he quickly learned that Alcaraz was one to watch after losing to the then unranked Spaniard and wanted to share a locker room with him.

He continued: “After the match we went to the same dressing room because I wanted to get to know him. He was already an incredible talent back then, you could see right away that he was a special player.

It was a nervous match – Alcaraz lost his serve five times and Sinner was broken seven times. And the 21-year-old remembers the ebb and flow.

“The match was a roller coaster but it was great,” he recalls. “I didn’t think at the time that we would share many tournaments or become the players we are today because it was impossible (to think that far ahead).”

Now just 23 and 21 years old, Sinner and Alcaraz have already enjoyed Hall of Fame-worthy careers. When they met in Alicante, they never imagined they would reach the top of the game together.

Alcaraz added: “When you’re that young, you don’t even think that far (forward). All dreams.