Jack Draper lost to Jakub Mensik in his first match since claiming the Indian Wells Open title.
The world number seven defeated Holger Rune on Sunday in California but fell at the first hurdle in the Miami Open.
He went down 7-6 (7-2) 7-6 (7-3) to Mensik on Saturday, despite having started in ideal fashion with a break of his opponent's serve.
Off-court chaos erupted during the second set when Brazilian fans who had gathered in the crowd in anticipation of seeing Joao Fonseca in action were informed that the youngster's match against Ugo Humbert had been moved to another court.
Draper was leading 4-3 at the time and asked the umpire to stop play due to the disruption, though the world number seven was unable to salvage a positive result.
1 - Jack Draper is the first Indian Wells Men's Singles Champion to lose in his opening match at the Miami Masters in the same season since Dominic Thiem in 2019. Rough. #MiamiOpen | @MiamiOpen @atptour @atptour
— OptaAce (@OptaAce) March 22, 2025
Fonseca, meanwhile, beat Humbert 6-4 6-3, while Reilly Opelka came from a set down to defeat Indian Wells runner-up Rune 4-6 6-3 7-6 (7-5).
Data Debrief: Reality check for Draper
It was a bad day at the office for Draper, who was perhaps suffering from his exploits in the Californian desert earlier this month.
The 23-year-old is the first Indian Wells men's singles champion to lose in his opening match at the Miami Open in the same season since Dominic Thiem in 2019.
Mensik, meanwhile, is one of only four active men with a positive record (6-5) against players ranked in the top 10. He joins an illustrious list featuring Jannik Sinner (42-32), Carlos Alcaraz (36-21) and Novak Djokovic (260-117).