Top seed Nick Kyrgios withdrew from the singles draw at the Delray Beach Open on Tuesday with a wrist injury, the tournament announced.
He was replaced by Daniel Elahi Galan, the tournament said.
"I'm dealing with a little bit of a left wrist injury; been dealing with it for the last week or so," Kyrgios said Monday, according to Tennis.com. "Some sort of tendon thing. Apart from that, feeling pretty good."
This was the first time Kyrgios was the top seed at an ATP event.
The 24-year-old Australian also withdrew from the New York Open earlier this month, with a shoulder injury.
Kyrgios, who is ranked No. 21 in the world, is 6-2 in singles matches this season.