World No 3 Daniil Medvedev and Australia's Nick Kyrgios have withdrawn from the US Open tune-up tournament in Washington due to injury, organisers said on Wednesday.
Medvedev, who won the US Open in 2021, has five titles this year with triumphs in Rotterdam, Doha, Dubai, Miami and Rome. The 27-year-old Russian reached the Wimbledon semifinals earlier this month, losing to eventual champion Carlos Alcaraz.
Defending Washington champion Kyrgios has missed every Grand Slam this year due to injuries to his knee, foot and wrist. He has only made it onto the court once, losing in straight sets at the Stuttgart Open in June.
The 28-year-old also won the Washington title in 2019 after beating Medvedev in the final.
This year's tournament runs from July 31 to August 6.
Japan's Kei Nishikori, Frenchman Gael Monfils and Kevin Anderson of South Africa have been given wildcards into the ATP 500 event, organisers said.
In the women's draw, former world No 3 Elina Svitolina and 2019 US Open champion Bianca Andreescu lead the list of wildcards.
Ukraine's Svitolina, 28, returned to tennis in April after giving birth to daughter Skai last October and has surged to world number 27 after reaching the French Open quarterfinals and Wimbledon semifinals.
American Sofia Kenin, who won the Australian Open in 2020, and compatriot Danielle Collins, this year's runner-up in Melbourne, are the other wildcard entries.
The US Open begins on August 28.