Australian tennis player Nick Kyrgios has withdrawn from the Terra Wortmann Open, also known as Halle Open, due to an ongoing issue with his left knee, the tournament organisers said on Monday.
He was scheduled to face Lorenzo Sonego in the Halle first round on Tuesday to make his second consecutive appearance at the German grass tournament.
Kyrgios has been replaced by the lucky loser Aslan Karatsev, who reached his maiden ATP Masters 1000 semifinal as a qualifier in May in Madrid.
The 28-year-old Australian made his comeback to the ATP Tour in Stuttgart last week after he had surgery to repair a small tear in his left lateral meniscus in January.
He complained of inhibited movement caused by his knee during his first-round defeat to Wu Yibing, however, and the problem has now forced Kyrgios' withdrawal from the ATP 500 in Halle.
Kyrgios enjoyed the best season of his career in 2022, when he racked up a 37-10 record, including a Tour-leading 12 wins on grass. That tally included his run to a maiden major final at Wimbledon.