Mirjana Lucic-Baroni stuns third seed Simona Halep

The third seed, who had also been the unlikely victim of the same Croatian surprise packet in the third round of last year's US Open, found history repeating itself as she crumbled after losing a tight first set.

Halep, who usually toys with her opponents, offering a mix of pace and accuracy, was the victim this time as she never found her stride on Court Suzanne Lenglen and could only summon up five winners against the 33-year-old world number 70.

Lucic-Baroni, who next plays French 29th seed Alize Cornet, ended Halep's resistance with an ace.

"She played well. I couldn't play my best today. But, you know, she started to hit the ball very strong at the beginning of the match. So she was better than me today," Halep told a news conference.

A subtle player, Halep was drawn into a hitting contest by Lucic-Baroni, who came back on the tour in 2006 after a three-year hiatus.

"I just wanted to hit too strong maybe, and to change the game is not good. I have to play like what I feel on court and to create the game," Halep said.

"So I started to hit the ball too strong, and that is not my style. I don't feel it, and I don't handle it."

Lucic-Baroni stayed true to her style -- poised and aggressive.

"I think she was trying a couple of different things, and I was just trying to stay aggressive and play smart and serve smart," she explained.

"She moves the ball around really well. She's an amazing athlete and super tough opponent. I was glad I was able to stay aggressive but not make too many unforced errors. That was the key for me."

21-Garbine Muguruza Blanco (Spain) beat Camila Giorgi (Italy) 6-1 6-4

19-Elina Svitolina (Ukraine) beat Yulia Putintseva (Kazakhstan) 1-6 7-5 9-7

Elena Vesnina (Russia) beat Polona Hercog (Slovenia) 2-6 6-1 6-3

11-Angelique Kerber (Germany) beat Ajla Tomljanovic (Australia) 6-3 6-2

Donna Vekic (Croatia) beat Bojana Jovanovski (Serbia) 6-4 6-3

Mirjana Lucic-Baroni (Croatia) beat 3-Simona Halep (Romania) 7-5 6-1

29-Alize Cornet (France) beat Alexandra Dulgheru (Romania) 6-2 7-5

2-Maria Sharapova (Russia) beat Vitalia Diatchenko (Russia) 6-3 6-1

Annika Beck (Germany) beat Paula Kania (Poland) 6-2 6-2

13-Lucie Safarova (Czech Republic) beat Kurumi Nara (Japan) 6-2 6-0

26-Samantha Stosur (Australia) beat Amandine Hesse (France) 6-0 6-1

20-Sabine Lisicki (Germany) beat Daria Gavrilova (Australia) 6-1 (Gavrilova retired)