Take notice: Former World No. 4 Kei Nishikori is playing at a high level in his first ATP Tour tournament in 21 months.

The 33-year-old defeated Chinese teen Shang Juncheng 6-4, 7-6(3) on Thursday to reach the quarter-finals of the Atlanta Open. The Japanese star Nishikori displayed vintage all-court coverage and absorbed the 18-year-old's firepower to advance. At 5/3 in the second-set tie-break, Nishikori won an exciting 21-shot rally to set up match point before sealing a spot in the last eight with an ace.

"It was a tough battle, but I was very excited on the court," Nishikori said in his on-court interview. "I felt pretty good, especially playing under [the lights]. I felt very good on the court today."

Nishikori will next look to extend his 3-0 Lexus ATPHead2Head series record against top seed Taylor Fritz.

The 12-time tour-level titlist Nishikori is competing in his first tour-level tournament since the BNP Paribas Open in October 2021. Nishikori underwent arthroscopic left hip surgery in 2022 and returned to the ATP Challenger Tour last month, immediately winning a title in Puerto Rico. Friday will be his first tour-level quarter-final since August 2021, when he made it to the last four of the ATP 500 event in Washington, D.C.

"It's always tough coming back from injury, I was out for almost two years," Nishikori said. "I just came back, played the last couple tournaments and coming into here, I'm feeling pretty good. Luckily I won two rounds here and happy to play another one tomorrow." 

Shang, who used a medical timeout at 2-3 in the second set to treat a right foot problem, earned his second tour-level victory this week when he upset fourth seed Ben Shelton in the opening round. The Beijing-native is 18th in the Pepperstone ATP Live Next Gen Race.