Carlos Alcaraz likely just played his tennis idol Rafael Nadal for the last time in their professional careers during Thursday's semifinal match of the Six Kings Slam. Although the score makes it look like Alcaraz ran away with the match at 6-3, 6-3, the 21-year-old admitted he still had to play his best in order to beat the 22-time major champion.

The Six Kings Slam is the most lucrative exhibition tennis tournament ever, taking place in Riyadh, Saudi Arabia, as part of the country’s annual sporting season.

In a recent interview with DAZN Sport, the 22-time major champion was asked to push the conversation further and compare the rivalries between him, Federer and Djokovic to the new rivalries being made between young players in tennis—like the battles between Carlos Alcaraz of Spain and Jannik Sinner of Italy.

Rafael Nadal, one of tennis's greatest icons, announced on Thursday that he will retire next month at age 38. The 22-time Grand Slam champion revealed the decision on social media. In the video, he states the upcoming Davis Cup finals in Malaga, Spain, will mark the end of his 23-year professional career.

Novak Djokovic and Rafael Nadal, who own 46 Grand Slam singles titles between them, will be among the tennis stars competing for the largest purse in tennis history.