Fifth seed Adrian Mannarino and sixth seed Gael Monfils have been beaten in the first round of the ATP event in Lyon, a week out from the start of the French Open.
World No.38 Monfils won the first set before being eliminated 2-6 6-4 6-4 by Germany's Maximilian Marterer.
Mannarino's disappointing run on clay continued as he suffered a 6-3 4-6 6-1 defeat to Guillermo Garcia-Lopez.
The Spanish world No.71 converted six break-point opportunities to inflict a fourth straight defeat on Mannarino, who also suffered early exits in Rome, Madrid and Barcelona.
The only French winner on Monday was veteran Gilles Simon, who accounted for Spanish qualifier Jordi Samper-Montana 6-4 6-2.
Others to progress to the second round were Spain's Roberto Carballes Baena, Dusan Lajovic of Serbia, Briton Cameron Norrie and Argentine Federico Coria.
