Feliciano Lopez of Spain quit because of a side muscle injury on Monday after losing the first five games of his first-round French Open match against Florent Serra of France.
The 15-seeded Lopez pulled the muscle while practicing at Roland Garros on Thursday.
“In the beginning, I felt it was nothing really serious, but (the) day after, I couldn’t play almost,” Lopez said. “I tried to rest during the weekend just to try to play today, but it was impossible.”