At the start of the 2022 season, American Ben Shelton was ranked No 573 in the world. Less than two years later, the 21-year-old will make his debut in the top 15 on Monday after winning his first ATP singles title on Sunday.

The big-hitting left-hander, who had never travelled outside the United States for a tennis tournament until the Australian Summer earlier this year, defeated Russian Aslan Karatsev 7-5, 6-1 to win the Japan Open at the Ariake Colosseum in Tokyo. The win makes Shelton the sixth first-time ATP singles champion in 2023 (joining Tallon Griekspoor – Pune, Wu Yibing – Dallas, Arthur Fils – Lyon, Chris Eubanks – Mallorca, Pedro Cachin – Gstaad).

Shelton now owns a 2-0 edge over Karatsev in career head-to-head, having beaten the Russian in the third round of the recent US Open in four sets.

Bryan and Ben Shelton become the fourth father-son duo to win an ATP singles title in Open Era

The American became the youngest player to triumph in Tokyo since then 20-year-old Lleyton Hewitt won here in 2001. It also makes him and his father, Bryan Shelton, the fourth father-son duo to win an ATP singles title in Open Era (Phil & Taylor Dent, Ramanathan & Ramesh Krishnan, Petr & Sebastian Korda).

En route to the final, Shelton, ranked No 19 this week, beat Japanese qualifier Taro Daniel (3-6, 6-4, 7-6 (2)), Australian Jordan Thompson (6-7 (5), 6-4, 6-3), No 5 seed Tommy Paul (7-6 (4), 6-3) and qualifier Marcos Giron (6-7 (2), 7-6 (5), 6-4).

Karatsev, ranked No 50 but assured of moving into the top 40 next week, had scored wins over American Frances Tiafoe, the No 6 seed (6-3, 7-6 (4)), Chinese Zhizhen Zhang (6-3, 6-4), Australian Alex De Minaur, the No 4 seed (6-3, 6-2) and Japanese wildcard Shintaro Mochizuki (6-3, 6-4) earlier in the week.