Reigning French Open champion Barbora Krejcikova is out of this year's tournament after suffering a first-round defeat to teenage opponent Diane Parry.

The number two seed looked to be cruising on Court Philippe-Chatrier, taking the first set 6-1, before an impressive recovery from Parry saw the 19-year-old take the next two sets 6-2 6-3.

Parry becomes the lowest-ranked woman to beat the second seed at Roland Garros since Arantxa Rus beat Kim Clijsters in 2011.

It looked like Krejcikova was going to follow number one seed Iga Swiatek in easing to a quick win on Monday, winning 15 straight points in the early stages as she ran out to a lead of 6-1 2-0.

However, her determined opponent suddenly found an extra gear and started to trouble the Czech star, actually winning a higher percentage of points on her second serve (67) than her first (64) to win six straight games in the second set.

Krejcikova broke in the first game of the deciding set and looked to have recovered, only for Parry to break back in the fourth game, before breaking again in the eighth, and serving out to claim a famous win.

The French youngster will face Colombian Camila Osorio in the second round.