Mackenzie McDonald (left) was beaten by Jannik Sinner as the Italian claimed his third ATP titleTeenager Jannik Sinner won the Citi Open in Washington on Sunday to claim the biggest title of his career.
The Italian, 19, beat the USA's Mackenzie McDonald 7-5 4-6 7-5 for his third ATP title.
Sinner also became the youngest winner of an ATP 500 event since the category was created in 2009.
"I'm not looking if I'm the youngest because the road is long," he said. "There's still much work to do. I'm already focusing on next week."
Sinner is the ATP's top-ranked teenager - he came into the tournament as the world number 24 and is set to jump to a career-high 15, with McDonald rising from 107 to 64.
World number five Alexander Zverev was the previous youngest ATP 500 winner, having triumphed at Washington in 2017, aged 20.
Sinner ended last year with a win in Sofia and started 2021 by winning in Melbourne, making him the youngest player to win back-to-back titles since Rafael Nadal, 19, in 2005.
His best performance in a Grand Slam event was a run to last year's French Open quarter-finals, and he made this year's fourth round.
Nadal aims to 'regain confidence' in foot for US Open
Sinner will make his third appearance at the US Open when the year's final Grand Slam begins on 30 August, and Spanish great Nadal aims to "regain confidence" in his fitness for the New York tournament by competing in Toronto this week.
The world number three, now 35, has not yet fully recovered after the recurrence of a foot issue that kept him out of Wimbledon and the Tokyo Olympics.
The 20-time Grand Slam winner suffered a shock third-round exit in Washington, in his first event since losing in the French Open semi-finals.
"It's been a couple of tough months for me in terms of physical issues," said the Spaniard. "I really need to have a couple of weeks with less pain to have the confidence again on my movements.
"I know I am not at my peak yet but I think I have been practising better than what I played in Washington so I am excited to keep going here and be able to play a little bit better."
