French qualifier Albano Olivetti, ranked 388th and playing in the main draw of an ATP event for the first time, stunned Mardy Fish in three sets on Thursday in the second round of the Open 13 tennis tournament in Marseille.

The second-seeded American rallied from a 3-1 deficit in the second set to level the match.

But Olivetti jumped out to a 3-0 lead in the decider and kept his composure to earn the biggest victory of his young career 6-3 3-6 6-3.

“That’s just a number next to his name right now,” Fish said of Olivetti’s ranking.

“He won’t be there for very long if he continues to play like that.

“The first time that I’ve ever seen him hit was when we warmed up for the match. Sometimes that happens and you have to adjust. His style of play is hard to adjust to.”

Fish compared Olivetti’s serve to Ivo Karlovic and John Isner.

“He puts pressure on you with his serve and that’s what big servers do,” Fish said.

“He probably has one of the hardest serves I’ve ever played against. He hit me with a serve and I almost hurt my left wrist.

“I had a rough time with his serve, for sure. When he’s down 15-40, he can come back with not only his first serve but his second serve – it’s almost just as good.”

Olivetti served 23 aces but also nine double-faults.

Olivetti will meet Michael Llodra in an all-French quarter-final.

Llodra downed sixth-seeded Alexandr Dolgopolov of Ukraine 6-4 5-7 7-6 (7-5).

Juan Martin del Potro also advanced to the quarter-finals when a right foot injury forced Nikolay Davydenko of Russia to retire with the match level at one set apiece.

The fourth-seeded Argentine lost the opening set 7-6 (8-6) but took the second 6-4 when Davydenko said he couldn’t continue.

“It was a really tough match,” del Potro said.

“But I’m glad to go through. Unfortunately, he can’t finish the match. And I wish him a fast recovery for the next tournament.”

Del Potro will next face Richard Gasquet, who cruised past Igor Kunitsyn of Russia 6-3 6-2.

“Here I have a really difficult draw,” del Potro said.

“It doesn’t look like a 250 tournament because the tournament has four top-10 (players). That means this tournament is very important and very high level.”

Del Potro paid tribute to the victims of Wednesday’s train crash in Buenos Aires by wearing a black ribbon on his T-shirt.

Fifty people died when the train crashed at a downtown station.