The 2021 Citi Open tennis tournament belonged to the future of men’s professional tennis. Aside from Rafael Nadal and the fanfare surrounding his appearance in D.C., one of the prominent storylines of the tournament was the emergence of the next generation of men’s tennis stars. Half of the semifinalists in the singles draw were 20 and younger, and in the end, 19-year-old Jannik Sinner of Italy defeated 26-year-old American Mackenzie McDonald, 7-5, 4-6, 7-5, on Sunday afternoon at Rock Creek Park Tennis Center to become the youngest winner of an ATP 500 tournament since the category was created in 2009.

With the win, Sinner also became the third-youngest men’s champion in D.C., behind 2001 champion Andy Roddick and 2008 champion Juan Martin del Potro. (Disclosure: City Paper owner Mark Ein manages the Citi Open.) Sinner, currently ranked No. 15 in the world, now has three ATP titles to his name, after winning the Sofia Open last November and the Great Ocean Road Open in Australia this February. But Sinner isn’t caught up in his own hype—or his record setting accomplishments as a teenager.

“When you see somebody is the youngest or whatever, I don’t put much weight on that,” Sinner told reporters after winning the Citi Open. “There are a lot of players who have done much, much better than me. It’s not about, you know, who is the youngest or whatever. I just want to improve, working hard … Obviously I’m very, very happy about this tournament and win today, but I’m not looking if I’m the youngest whatever, because the road is long.”

Still, the members of the Next Gen, defined by the ATP Tour as players 21 and younger, made their presence known in D.C. En route to the title, Sinner beat 20-year-old Sebastian Korda in the third round, then teamed up with him to reach the semifinals of the doubles draw. Sinner went on to defeat 20-year-old American Jenson Brooksby in the singles semifinals. Brooksby upset, in order, Kevin Anderson, Frances Tiafoe, No. 2 seed Felix-Auger Aliassime, and John Millman to reach the final four. American Brandon Nakashima, who turned 20 on Aug. 3 during the tournament, reached the third round.

The performance of his peers isn’t lost on Sinner.

“It’s nice, I think, to see, especially for the tennis world, getting new names on it,” he said. “Everyone is a great, great player, great athletes. Everyone has his own team which I think is very impressive. Everyone is so competitive, and that’s very nice. Nobody wants to lose one single point. It’s great to see a lot of Americans, young guys like Nakashima, Brooskby, Korda, they are getting very, very good. Talking about all the rest, [Lorenzo] Musetti, [Carlos] Alcaraz, and everyone. I don’t want to miss anybody of them, because I think it’s going to be very, very exciting.”

In their first meeting on Sunday, Sinner and McDonald engaged in a back-and-forth match that could have gone either way. Even though Sinner dictated points with his pace throughout the nearly three-hour match in hot and sunny conditions, McDonald fought back while under pressure on the biggest points. The California native saved 10 set points in the opening set and 16 break points in the match. McDonald, who had never reached an ATP Tour final before, also saved a pair of championship points when Sinner led 5-2 in the deciding third set before tying it at 5-all.

Ranked No. 107 during the tournament, McDonald jumped 43 spots in the ATP Tour rankings to No. 64 with his run.

“I’m happy with how I competed, how I played,” he said. “I feel like I really put everything out there. Maybe could have played a little bit better at times and served a little bit better, in my opinion. But I did everything I could expect of myself, and I’m very happy with the week overall and my progress as a player.”

Sinner, too, is happy about his performance, but after the tournament, in which he only dropped one set, the Citi Open champion, who turns 20 on Aug. 16, also spoke of how much he still needs to improve.

“I think there is still much work to do, to be honest,” Sinner said when asked if he felt he could compete with the best in men’s tennis. “A lot of experience to put in, working hard as we are doing now, and trying to play important matches, important matches and important moments of a match. Today I think I had a lot of them. I can learn many things about today.”