Kei Nishikori said his Bank of China Hong Kong Tennis Open clash with Karen Khachanov on Wednesday would provide an acid test for whether he could still compete with the world’s top 20 players.

Japan’s former world No 4 Nishikori, a US Open finalist in 2014, missed all of the 2022 season and played only four tournaments in 2023, because of a succession of serious injuries.

Returning in 2024, his world ranking sank to the depths of No 581 in July. A gutsy competitor and 10-time grand-slam quarter-finalist, Nishikori responded to that low with a series of strong performances culminating with success at November’s Helsinki Challenger event, to climb to the fringes of the top 100.

Beginning his 2025 campaign in Hong Kong this week, Nishikori swept aside an under-the-weather Denis Shapovalov in round one on Tuesday. He anticipated a much sterner test against two-times grand-slam semi-finalist Khachanov, the world No 19, in the day’s showpiece match at Victoria Park Tennis Centre.

“He has been playing well, especially towards the end of the 2024 season,” Nishikori said. “He has a big serve and big forehand, so it will be a good challenge for me to see if I can play with the top-20 guys.

“My next goal is to reach the top 50, but I have to go slowly, take one tournament at a time, stay healthy and play good tennis all year, then I can do it.”