For the first time in three years, Novak Djokovic failed to reach the round of 16 in an event.
The world's top-ranked player lost 6-4, 2-6, 6-4 to Jiri Vesely on Wednesday in a second-round match at the Monte Carlo Rolex Masters.
Djokovic, who had a first-round bye in this clay-court event, said of Vesely, "He played very solid. He was serving very big. He was playing tactically good and aggressive. When he was a break up in the third set, he was playing bravely. He was coming in, (hitting) drop shots, big serves. He was going for it. He deserved to have it. ...
"I have to congratulate the better player today on the court and just move on from there. It is what it is. Sometimes you don't play your best and you lose."
Vesely, a 22-year-old Czech player who is ranked 55th in the world, moves on to a third-round match against Gael Monfils of France. Monfils, the 13th seed, beat Italy's Paolo Lorenzi 6-2, 6-4.
Vesely lost in the first round in six of his first seven tournaments this year before getting to the semifinals last week in Marrakech, Morocco.
The upset of the 28-year-old Serbian star marked Vesely's first victory over a top-10 player.
"I'm just very, very happy," Vesely said. "When I went on court, I had completely different thinking, like, 'I hope to win a game,' or 'I really hope to do well.' But I really had no idea that I really would be able to beat Novak today."
In other second-round action Wednesday, second-seeded Andy Murray topped qualifier Pierre-Hugues Herbert 6-2, 4-6, 6-3; third-seeded Roger Federer defeated Guillermo Garcia-Lopez 6-3, 6-4; fourth-seeded Stan Wawrinka knocked out Philipp Kohlschreiber 7-6 (2), 7-5; and fifth-seeded Rafael Nadal beat Aljaz Bedene 6-3, 6-3.
Qualifier Damir Dzumhur of Bosnia and Herzegovina upset sixth-seeded Tomas Berdych 6-4, 6-7 (1), 6-3.