France's Gael Monfils and Gilles Simon suffered early exits from the Cincinnati Masters on Tuesday.
American James Blake, a former world number four, crashed out of the tournament in just 45 minutes but his compatriot Mardy Fish battled into the second round.
Fish produced a spirited display to defeat Simon 7-6, 7-5 and set up a match with Spanish eighth-seed Fernando Verdasco.
Monfils, the 16th seed, fell to Colombian qualifier Alejandro Falla 6-3, 6-4 while Blake's slide down the rankings continued with a 6-3, 6-0 loss to Uzbekistan's Denis Istomin.
The good news for France came with Richard Gasquet defeating 12th seeded Russian Mikhail Youzhny 2-6, 6-4, 6-1.
Czech seventh seed Tomas Berdych, the Wimbledon runner-up, began his campaign against Frenchman Paul-Henri Mathieu in straightforward fashion with a 6-4, 6-4 win in his second round match.
The top seeds, including world number one Rafael Nadal, begin their second-round matches on Wednesday.
Nadal will face American Taylor Dent while Roger Federer takes on Istomin and Britain's Andy Murray faces Frenchman Jeremy Chardy.
