Cheered on by a crowd of childhood mates, Valentin Vacherot walked a third-set tightrope in his home-town tournament before beating Alex de Minaur 6-4, 3-6, 6-3, on Friday to gatecrash the semifinals at the Monte Carlo Open.
The unseeded Monegasque, born a stone's throw from the tournament venue in Roquebrune-Cap-Martin and playing at "my club", joined the top three seeds in the semifinals.
He will face top-ranked Carlos Alcaraz on Saturday. World No 2 Jannik Sinner plays Alex Zverev.
"That sounds amazing," said Vacherot. "Such an honour for me to be part of the semifinals with the three best in the world over the last few years."
Alcaraz and Sinner both cruised through with straight-sets wins earlier on Friday.
Alcaraz extended his clay-court run of victories to 16 as he crushed Alexander Bublik 6-3, 6-0.
Sinner extended his winning run at Masters 1000 events to 20 matches as he brushed aside Felix Auger-Aliassime 6-3, 6-4.
Zverev battled past Brazilian teenager Joao Fonseca 7-5, 6-7 (3/7), 6-3.
Vacherot ended the day by giving his fans a roller-coaster ride.
He started by racing 4-1 ahead against fifth-seed De Minaur but allowed the Australian to level before breaking in the 10th game to take the first set.
De Minaur broke twice to take the second set.
The Monegasque grabbed the third set initiative with a fifth-game break but almost handed it straight back before saving a break point in the next game.
On Vacherot's next service game, De Minaur raced to a 0-40 lead, but cheered on by the crowd, Vacherot saved all three and then a fourth, before holding.
"I know myself, unhappily I do this so often, I drop a bit at the start of the game, then I recover, even from 0-40, thanks to my serve," said Vacherot.
Vacherot galloped to two match points in the next game. De Minaur saved both with drop shots that crept over the net. When the Australian tried the trick again, Vacherot anticipated to earn a third match point which he took with a blazing forehand.
Roared on by the crowd all evening, Vacherot planted his feet tilted his head and roared back.
"All the guys up there chanting are all my best friends from when I was nine, 10 years old," he said. "It is rare for a player to have this chance."
"I am so lucky to have a tournament in my club. I can name 1 000 faces in the crowd."
Vacherot, who was ranked outside the top 200 before he won in Shanghai in October, climbed to 16 in the ATP live rankings.
'A STEP FORWARD'
Sinner, who had said his energy level was not right when he dropped a set the day before, was happier with his form.
"I feel like it was a step forward today," said the Italian after beating Canadian Auger-Aliassime.
Alcaraz, playing Bublik for the first time, broke in the opening game and had four break points in the third game but could not take any.
Bublik broke back in the fourth game and led 3-2, but Alcaraz won the next 10 games as he raced to victory.
"I started the match pretty well," Alcaraz said.
"I had points to be two breaks up and didn't make it and then I lost a bit of the feeling on the ball.
"I had to run side to side a lot, had to defend and then a few games gave me a lot of confidence in the match. I was playing aggressively and I played a great and solid match against a player that you don't know what they will produce next."