The 30-year-old, a finalist at Flushing Meadows in 2014, withdrew from the Western & Southern Open hard court warm-up event after his first positive test last week. “Just a little update. I took another COVID test and I am still positive. I have very minimal symptoms and I am staying in full isolation in Florida,” Nishikori posted on social media late on Friday.

“The next test will be early next week. We will update you with more information.” Nishikori, who has been staying at the IMG Academy in Florida, has enjoyed his greatest Grand Slam success at the US Open, reaching the semi-finals in 2016 and 2018 in addition to his loss to Marin Cilic in the 2014 title decider.