Keothavong, however, was bagelled in the deciding set of her prelim opener by Czech player Birnerova after the two ladies traded sets at 6-3 apiece.
Another qualifying hope on the WTA side, British number five Tara Moore, was beaten in straight sets by Bulgarian-born Kazakh Sesil Karatantcheva 6-3 6-3.
The two highest-ranked British females, Laura Robson and Heather Watson, will proceed straight to the main draw which happens on Friday.
The clay Grand Slam in France begins properly on Sunday.
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