Former champions Novak Djokovic, Rafa Nadal and Serena Williams have all entered next month's Western & Southern Open in New York, which will serve as a tune-up for the US Open.
Organisers of the August 20-28 event, which was relocated from Cincinnati this year because of the coronavirus, said defending champions Daniil Medvedev and Madison Keys are also among the initial entries.
The tournament will be staged in a quarantine environment without spectators at the National Tennis Center in Flushing Meadows, where the Grand Slam hardcourt showdown is set to begin on August 31 in similar conditions.
The ATP Masters 1000 event will be the first on the men's calendar since play was suspended in March because of the virus.
Among the other early entries on the men's side – which includes 40 of the top 43 ranked ATP players – are world No 3 Dominic Thiem, 2017 champion Grigor Dimitrov and Marin Cilic, who won in 2016.
The only top-10 men's players not on the entry list were injured Swiss star Roger Federer, the world No 4, and France's ninth-ranked Gael Monfils.
World No 3 Karolina Pliskova, who won the event in 2016, is the highest-ranked player on the women's side that will feature 39 of the top 53 players in the world, including teen sensation Coco Gauff.
Among the absent are Australia's top-ranked Ashleigh Barty, the reigning French Open champion, and world No 2 Simona Halep of Romania
The women's WTA Tour will signal the return of the professional circuit with the Palermo Ladies Open in the Sicilian capital from Monday.
