World number two Daniil Medvedev suffered a shock first-round exit at the French Open when he lost 7-6 6-7 2-6 6-3 6-4 to Brazilian qualifier Thiago Seyboth Wild amid gusty winds on Tuesday.
Although Seyboth Wild won two Challenger (second-tier) titles on clay this season, Medvedev was coming into the Grand Slam tournament on the back of a title in Rome, having shown tremendous progress on the slowest surface.
It counted for nothing on a windswept court Philippe Chatrier, where the Russian seemed increasingly frustrated, arguing with the umpire and the fickle Paris crowd over a line call in the fourth set.
Seyboth Wild just had too much pace and power for Medvedev, who never found his range and capitulated after four hours and 15 minutes.
"I watched Daniil play since I was junior and beating him on such a court is a dream come true," the world number 172 said.
Elsewhere, Alexander Zverev earned a 7-6 7-6 6-1 first-round win over South African Lloyd Harris on his return to Roland Garros a year after sustaining a serious ankle injury during his semi-final against eventual champion Rafa Nadal.
The German will next face Slovakia's Alex Molcan, who saw off home hope Hugo Gaston in straight sets.
Norway's fourth seed Casper Ruud, runner-up last year, eased to a 6-4 6-3 6-2 win over Swedish qualifier Elias Ymer in the first round as he bids to reach a second straight Paris final.
In the women's draw, Wimbledon champion Elena Rybakina continued her fine run on clay and moved into the second round after easing to a 6-4 6-2 win over promising Czech teenager Brenda Fruhvirtova.
Earlier, 2021 winner Barbora Krejcikova crashed out after a 6-2 6-4 defeat to Lesia Tsurenko of Ukraine, while last year's finalist Coco Gauff shook off an error-strewn opening set to overcome Spaniard Rebeka Masarova 3-6 6-1 6-2.
Tunisia's Ons Jabeur, who suffered a shock first-round exit last year, made a strong start to her campaign as the seventh seed cruised to a 6-4 6-1 win over Lucia Bronzetti of Italy.