In Tokyo, qualifier Alex Michelsen stunned fourth seed Stefanos Tsitsipas 4-6, 6-1, 6-2, marking his first Top 20 victory since May. Tsitsipas, who appeared unwell during the match, dropped all five break points against his serve.
Michelsen, playing his first event since the US Open, improved to 25-24 on the season. The 20-year-old has finished runner-up twice this season at the 250 level in Newport and Winston-Salem.
In other action, Tommy Paul brushed aside Matteo Arnaldi 6-3, 6-2. The No. 5 seed did not face a break point, thanks to his 15 for 17 success rate on his second serve. Paul is looking to make up ground in the ATP Finals race, currently ranked No. 11.
Yoshihito Nishioka gave home fans a thrilling win, outlasting Felix Auger-Aliassime 7-6 (5), 3-6, 7-6 (5). Nishioka saved two match points on his serve at 5-6 in the decider.
Fellow lefty Jack Draper also emerged victorious, beating Mattia Bellucci 6-4, 6-2. The US Open semifinalist will face second-seeded Hubert Hurkacz in the second round.
