Federer, who would have met Stefanos Tsitsipas, has an injury in his right leg. 37-year-old has refrained from betting on the gravel the last few years for health reasons, but recently returned. He has not played grand slam tournament in Paris since 2015, and there is now a concern over whether there will be any comeback of the year.
Both the swiss and japanese Naomi Osaka played two matches on Thursday because Wednesday's game rained away. Perhaps it became too tiring for them.
Osaka entered the pain in the hand when she withdrew from the quarter-finals against Kiki Bertens.