The former World No.4 ousted sixth seed Alexis Galarneau 7-6(3), 6-1 in the first round of the Chicago Men’s Challenger, where rain forced the event to move indoors on Wednesday. Nishikori won 47 per cent of his return points and raced to a 5-0 lead in the second set, eventually converting his third match point to advance after one hour, 24 minutes.

World No. 215 Galarneau is the highest-ranked player Nishikori has beat during his 2023 comeback. The Japanese star will next face Skander Mansouri or James McCabe in the second round.

The 33-year-old Nishikori, who underwent arthroscopic left hip surgery last year, returned to action last month at the ATP Challenger event in Palmas del Mar, Puerto Rico. Despite playing his first tournament since the BNP Paribas Open in October 2021, the 12-time tour-level titlist dropped just one set all week en route to the title. Nishikori also played last week’s Cranbrook Tennis Classic in Bloomfield Hills, Michigan, where he fell to American Denis Kudla in the second round.

Nishikori, who is World No. 501 in the Pepperstone ATP Rankings, will return to ATP Tour action later this month in Atlanta and Washington, D.C.

Fans can watch all ATP Challenger Tour matches live and on demand for free at Challenger TV.