Last year's runner-up, Lorenzo Musetti, suffered an upset at the hands of the Monegasque player Valentin Vacherot, who advanced to the Rolex Monte-Carlo Masters Round of 16 for the first time on Wednesday.
World No. 23 Valentin Vacherot wrapped up an action-packed day at the Monte-Carlo Country Club with an historic 7-6(6), 7-5 win over world No. 5 Lorenzo Musetti in two hours and nine minutes on Court Rainier III.
In his on-court interview, the 27-year-old commented: "If someone had told me that my first Top 5 win of the season, second after Shanghai, would be here on a night session, on the centre court that I’ve been hitting on since I was six years old, I wouldn’t have believed it.”
With the win, the Monegasque equaled the best result by a local player in the Open Era, reaching the round of 16 at the Rolex Monte-Carlo Masters, 20 years after his half-brother and coach, Benjamin Balleret, progressed to the third round.
Next, the unseeded player who advanced to the last 16 at the Miami Open will face Pole Hubert Hurkacz for a place in the quarterfinals.
Earlier, the former world No. 6 took down Fabian Marozsan in straight sets, securing his spot in the next round.
An enthralling opener saw the home favorite fending off a set point in an edgy 72-minute first set tiebreak 7-6(6) to prevail over the fourth seed, who last year reached his maiden Masters 1000 final at the event.
Musetti opened with an encouraging break in the opening game; however, Vacherot broke straight back and held to love, inching ahead 2-1.
From there, they rallied through extended baseline exchanges, holding their ground. As a result, the first set was decided in a tiebreaker that the Monegasque took with confidence.
Relentless, the reigning Shanghai champion saved two of the three break points he faced across the first set, hitting fewer winners than the Italian, 10 to 18, and 14 against 24 unforced errors, respectively.
In the second set, they went toe-to-toe until Vacherot converted a break and held to move closer to victory at 5-3.
Then, he failed to serve for the match, conceding his serve to the 24-year-old, who set the score even at 5-5, keeping his hopes alive.
Unrelenting, the Monaco native broke straight back in the 11th game and finished off the upset by holding to close out 7-5, hitting an ace in the process.
"Let’s say I needed a set and a half to get on it in the first round," he added. "Now my game is back.”
Vacherot and Hurkacz will meet for the first time on Thursday, in the day session.
Elsewhere, wild card Matteo Berrettini shocked seventh seed Daniil Medvedev 6-0, 6-0 in just 50 minutes.
Assessing his performance, the 10-time ATP title holder said, "It was one of the best performances of my life. I missed three shots in the entire match, and it is not easy against a tricky player like Daniil.
"I think the game plan was perfect, and my weapons were working."
The Italian, who is yet to drop a game at the venue, delivered high-level tennis playing in his fifth clay-court tournament this season.
Meanwhile, Medvedev's erratic performance on a surface that is not his favorite cost him a maiden loss on Tour without winning a game.
Berrettini will next face Brazilian teenager Joao Fonseca, who came through Frenchman Arthur Rinderknech 7-5, 4-6, 6-3 in two hours and 33 minutes on Court des Princes.