Last year's runner-up Simona Halep crashed out in the French Open second round after a shock 7-5 6-1 defeat to Croatia's Mirjana Lucic-Baroni.
Halep, who was beaten in three sets by Maria Sharapova in the final 12 months ago, was unable to cope with Lucic-Baroni's aggressive hitting and lost in just one hour and 11 minutes.
It is the first time the Romanian has failed to reach the third round of a grand slam since 2013.
World number 70 Lucic-Baroni will now play France's Alize Cornet, who came from a set down to beat Italian Roberta Vinci 4-6 6-4 6-1.
Second seed Sharapova experienced no such problems as she cruised past Russia's Vitalia Diatchenko 6-3 6-1.
Sharapova has reached three consecutive finals at Roland Garros and the defending champion looked in impressive form, hitting five aces and 24 winners during the contest.
She will now play Australia's Samantha Stosur, who was the 2010 runner-up in Paris but who lost to Sharapova in three sets in last year's round of 16.
"She is always a tough opponent," Sharapova said.
"She enjoys playing on clay and benefits a lot from this surface. It will be a tough match but I have a pretty good record against her.
"I enjoy our matches. I hope I can continue that."
Sharapova added: "She has a very heavy ball, and I think on clay specifically it just really penetrates through the court.
"S he has one of the best kick serves in the game and she slices a lot. There are a lot of untraditional things that she does, but I enjoy that challenge."
Stosur thrashed French wildcard Amandine Hesse 6-0 6-1 and admits she will have to raise her game to beat the world number two.
"Maria is always a big challenge for me. No matter what surface it's on, I don't have a very good record at all," Stosur said.
"Obviously we played last year. That's the last time we played against each other so it's always a big challenge, and I've got to be ready to have to play as well, if not better than what I have been doing."
Source: PA
