Nick Kyrgios has withdrawn from Altanta with an ongoing hip injury, officials announced.
The 22-year-old Australian was the defending champion at the tournament.
"Having to make the decision not to defend my title at the BB&T Atlanta Open was really tough and disappointing," said Kyrgios in a statement, adding that his hip was "just not ready."
Kyrgios began re-experiencing hip problems following a fall on the grasscourts at Queens, and retired with the injury in the first round at Wimbledon. Photos were published of him at a nightclub with two younger female players the following night, apparently creating a rift with his girlfriend, Ajla Tomljanovic.
Kyrgios is still scheduled to play the ATP event in Washington.