The top-seeded Bartoli was trailing 6-4, 1-0 against Germany's Andrea Petkovic when she decided not to play on, having earlier called for a medical time-out at 5-4 down in the first set.
Seeded 11th for Roland Garros, the top-ranking French player is due to play Georgia's Anna Tatishvili in the first round of the French Open on Monday.
"It's really disappointing because I had been playing well but then the pain rapidly started to get worse," she said.
"It's awful, but you just have to accept it. I've got one and a half days to recover. We will see how the pain develops. Time to pray for a miracle."
- AFPTags: sport, tennis, france