Australian star Nick Kyrgios withdrew from his Indian Wells Masters quarter-final showdown with Roger Federer on Friday, blaming food poisoning for a sudden illness.
"Unfortunately I am unable to play today due to sickness," Kyrgios said on Twitter. "At this stage we think it's food poisoning, and I'm praying it's nothing more."
Kyrgios had been due to face Federer after knocking out Novak Djokovic in the last 16 on Wednesday.
Kyrgios's sudden illness is a cruel twist of fate for the talented 21-year-old, who has shown signs of finally starting to deliver on his promise in recent weeks after a young career marked by controversy.
His stylish win over Djokovic was the second time in as many weeks he had beaten the former world number one after also defeating the Serb in Acapulco.
In his statement on Friday, the world number 16 said he had taken the decision to pull out in California with a heavy heart.
"After a restless night of being sick I have nothing left and to play a great champion like Roger I need to be at my best to have a chance," Kyrgios said.
"I don't take this decision lightly, these are the matches we train for, but I'm in no fit state to take to the court," he added.
"I'm sorry to the fans... but I have to put my health first and I hope you understand."