Serena Williams' former coach, Patrick Mouratoglou, made his feelings clear about Carlos Alcaraz's prospects of becoming the best of all time in the future, despite Jannik Sinner being one of his biggest challenges. The Spaniard celebrated his US Open win on September 7, 2025.Alcaraz earned his sixth Grand Slam title at the 2025 US Open, after dominating the finals showdown against Jannik Sinner and claiming a 6-2, 3-6, 6-1, 6-4 win against him. The duo has locked horns with each other consecutively in the finals of the last three tournaments, and overall, has faced each other five times in the finals so far this year.The Spaniard showcased his potential by winning four out of five finals against the Italian. Reflecting on this, Serena Williams' ex-coach, Mouratoglou, made a bold claim about Alcaraz having the potential to become the best of all time despite Sinner being a challenge. Analyzing the World No. 1's future in the tennis world, he said:"Carlos is in advance compared to anyone else in the history. Since his first Grand Slam win in 2022 US Open, he won 1 Grand Slam out of 2. He's going to play atleast 10 more years, probably 15. If he keeps the same rhythm, he's going to beat the record of all times," said Mouratoglou.Highlighting the possibility of Carlos Alcaraz and Sinner going head-to-head in the coming future, like Rafael Nadal and Roger Federer, Mouratoglou added:"We can already think about it, of course anything can happen. He can get bad injuries. Maybe Sinner is going to find solutions against him in the future. It reminds me of the time when Roger and Rafael were dominating tennis so much, before Novak came in. So this is going to be the story of the next 10/15 years, the two guys progressing, the two guys knowing each other better and better and finding solutions."And maybe a third guy is going to enter. Who knows? So that's why it's a bit early to think abo ut that but I just want people to realize that Carlos is on a pace to become the best of all time," said Mouratoglou. View this post on Instagram Instagram PostFollowing this win, Alcaraz showed off his luxury Rolex watch during his US Open champion's photoshoot.Carlos Alcaraz makes his feelings known about becoming World No. 1 after the US Open win After his incredible performance at the US Open finals, Carlos Alcaraz sat for his final press conference for the tournament, where he opened up about earning the World No. 1 rank and ending Jannik Sinner's 63-week-long streak.Making his feelings known about this feat, the Spaniard said that it was an amazing feeling for him and revealed that claiming the top rank was one of his goals entering the 2025 season."Well, it's great when you achieve the goals you set up yourself at the beginning of the year. It feels amazing. So, since I got the chance to recover the No. 1, it was one of the first goals that I had during the season just to try to recover the No. 1 as soon as possible or end the year as a No. 1," Carlos Alcaraz said.Carlos Alcaraz further said that achieving the rank once again was like a dream come true for him, and accomplishing this while winning another Grand Slam title has made it even better.