Alex Michelsen surges past ailing Stefanos Tsitsipas in Tokyo; Tommy Paul cruises
Elsewhere Thursday, home favorite Yoshihito Nishioka saved two match points before edging Felix Auger-Aliassime.
The wild card prevailed in a final-set tiebreaker Thursday, but struggled to get up following his hard-fought victory.
Nishioka is looking for his second ATP singles title of the year, the first being ATP Atlanta in July.
The top seed prevailed, 7-6 (2), 6-1, over the Japanese left-hander on Tuesday at the Zhuhai Championships.