Three-time champion Serena Williams was stunned in the French Open third round by unseeded American Sofia Kenin.

Williams, 37, was seeded 10th but lost 6-2 7-5 to her 20-year-old compatriot, who was at times booed by the crowd.

The defeat means Williams’ quest to equal Margaret Court’s record of 24 Grand Slam singles titles continues.

“I’m so happy with this win – obviously you can tell with these emotions,” a crying Kenin told the crowd on Philippe Chatrier.

“Playing against Serena, you have to fight for every point.”

Williams’ defeat followed the¬†shock exit by world number one Naomi Osakaa few hours earlier and leaves only three top-10 players in the women’s draw.

Earlier in the day, defending champion Simona Halep enjoyed a straightforward 55-minute victory, beating Ukraine’s Lesia Tsurenko 6-2 6-1 to reach the last 16.

World number 35 Kenin will play Australian eighth seed Ashleigh Barty in the fourth round, while Halep faces unseeded 18-year-old French Open debutant Iga Swiatek.