Richard Gasquet's rich vein of form came to an abrupt halt when he lost to Gilles Muller in the opening round of the Open 13 in Marseille.
The Frenchman, one of five top-10 players competing this week, dropped the first set but levelled the match and raced into a 5-2 lead in the decider.
But his Luxembourg opponent's risk-all policy paid off when he hit back to take the third set tie-break and win 2-6 6-4 7-6.
Fifth seed Gasquet had previously won 15 of 17 matches this year, picking up titles in Doha and Montpellier.
"I was a catastrophe from the moment I went 5-2 up," he admitted.
"It is me who committed the mistakes. I was a little tired but at the same time I was eager to do well here. This match was not to be for me.
Compatriot Benoit Paire also bowed out, beaten by India's Somdev Devvarman who has slumped to 354 in the rankings.
And there was further disappointment for home fans in the late match when Gael Monfils crashed to Marcel Granollers of Spain, 6-4 6-4.
It wasn't all doom and gloom for the home players as Michael Llodra eased through to the second round by beating Belgian David Goffin 6-2 6-4.
Ernests Gulbis of Latvia defeated Finn Jarkko Nieminen 6-3 6-2 while Russian veteran Nicolay Davydenko overcame Sergiy Stakhovsky of Ukraine 6-2 4-6 6-2.