Seyboth Wild, who came through the qualifiers and had never previously won a Grand Slam match, triumphed 7-6 (7/5), 6-7 (6/8), 2-6, 6-3, 6-4.
It was Medvedev's fifth loss in the opening round at Roland Garros in seven appearances.

"I have watched Daniil play in my junior years. It's a dream come true to beat these kinds of players on this court," said the 23-year-old Brazilian who unleashed 69 winners.

"I was cramping in the second set and couldn't really serve the way I wanted to but I tried to play my best tennis."

Seyboth Wild, without a win on the main tour since February 2022, held his nerve in the conclusion of the four-hour 15-minute match on Court Philippe Chatrier.

He twice saw breaks retrieved by Medvedev in the deciding set before finally backing up a third break with a hold for 5-3. Two giant forehands secured victory.

He will face either Guido Pella or Quentin Halys for a place in the last 32.

Medvedev arrived in Paris buoyed by winning his first ever clay court title at the prestigious Italian Open last week for his fifth trophy of 2023.."Every time the clay court season finishes, I'm happy," said Medvedev.

Five-hour marathon
                  
Coco Gauff, the 2022 runner-up, battled to a 3-6, 6-1, 6-2 success over Rebecca Masarova of Spain but Barbora Krejcikova, the 2021 champion, was knocked out in the first round for a second successive year, losing 6-2, 6-4 to Lesia Tsurenko of Ukraine.

Wimbledon champion and fourth-ranked Elena Rybakina brushed off a slow start to dispatch Czech teenager Brenda Fruhvirtova 6-4, 6-2.
Fourth seed Casper Ruud, the runner-up to Rafael Nadal last year, eased past Swedish qualifier Elias Ymer 6-4, 6-3, 6-2.

Alexander Zverev, who suffered a season-ending ankle ligament injury in his 2022 semi-final loss to Nadal, secured a fourth win in four matches against Lloyd Harris of South Africa. German 22nd seed Zverev came through 7-6 (8/6), 7-6 (7/0), 6-1.

Danish youngster Holger Rune, seeded six, came through a tough test against American Christopher Eubanks, winning 6-4, 3-6, 7-6 (7/2), 6-2.
"It was super difficult. There are always nerves coming into the first round and Chris was playing very freely," said Rune who made the last-eight in 2022.

Italian qualifier Andrea Vavassori saved five match points to knock out Serb 31st seed Miomir Kecmanovic in a five-hour 10-minute epic.
Vavassori hit a colossal 106 winners in his 5-7, 2-6, 7-6 (10/8), 7-6 (7/3), 7-6 (11/9) win.