Kei Nishikori produced a high level Thursday to reach the quarter-finals at the Chicago Men’s Challenger. The Japanese star absorbed Tunisia’s Skander Mansouri hefty serve and struck the ball cleanly en route to a 7-6(1), 6-4 second-round victory at the ATP Challenger Tour 75 event.

Despite having six break points in the first set, four of which came in the seventh game, the 33-year-old Nishikori was forced to a tie-break. The 12-time tour-level titlist stayed steady from the baseline and capitalised on any look on return, capturing 70 per cent of points behind Mansouri’s second delivery throughout the one-hour. 42-minute contest.

Another victory in Chicago 💪@keinishikori defeats Mansouri 7-6, 6-4 to set up a quarterfinal encounter against Michelsen!#ATPChallenger pic.twitter.com/kuk6uzfq3o

— ATP Challenger Tour (@ATPChallenger) July 14, 2023

Rain forced the 27-year-old Mansouri to play his first-round match in the morning, when he defeated Australian James McCabe 3-6, 6-4, 6-4, before clashing against Nishikori.

The former World No. 4 Nishikori underwent arthroscopic left hip surgery last year and 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, Nishikori dropped just one set all week en route to the title. He will return to ATP Tour action later this month in Atlanta and Washington, D.C.

Nishikori, who has won eight of nine matches during his comeback, will next meet 18-year-old American Alex Michelsen in the last eight Friday.

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