Arnaud Clement thrilled home fans by knocking out top seed Marcos Baghdatis of Cyprus in the first round of the Lyon indoor tournament on Tuesday.
Clement, who won the event in 2000, needed just over two hours to beat France-based Baghdatis 6-2, 5-7, 6-3.
After taking the first set in 28 minutes, Clement opened a 5-2 lead in the second and served for the match at 5-4.
The Frenchman then showed signs of nerves and allowed Baghdatis to win the set but he was back in control for the decisive set, building a 3-0 lead before cruising to victory.
The defeat means Baghdatis faces a struggle to make the season-ending Masters Cup and has to shine at the Paris Masters next week to stand a chance of going to Shanghai next month.
"It's very frustrating," he said. "Since recovering from a shoulder injury I'm finding it hard to recapture my best tennis. It looks like my dream of making the Masters Cup will not
In late action fourth seed Richard Gasquet of France also advanced but he was made to work before beating former world number one Marat Safin 6-4, 7-6.
Gasquet won the second set tiebreak 7-5 with a controversial service winner on match point.
"That service winner on match point was clearly out," said Safin. "I know we're in France but still."
Safin is now looking forward to next week's Paris Masters, a tournament he has won three times.
"I hope to do well there because it's one of my favourites tournaments but a lot will depend on the draw," he said.
Argentine baseliner Gaston Gaudio, the second seed, was earlier hammered 6-0, 6-2 by unheralded German Simon Greul.
The 2004 French Open champion was never in contention in a surprisingly one-sided match that lasted only 55 minutes.