Paris, France (SportsNetwork.com) - Reigning champion Maria Sharapova was an easy second-round winner, while last year's runner-up Simona Halep was a shocking loser Wednesday at the French Open.

The second-seeded former world No. 1 star Sharapova blew past fellow Russian Vitalia Diatchenko 6-3, 6-1 on Court Chatrier, while 33-year-old Croat Mirjana Lucic-Baroni vanquished the third-seeded Romanian Halep 7-5, 6-1 in 71 minutes on Court Lenglen.

Halep crumbled after dropping the first set, striking a mere five winners in the match against her 70th-ranked counterpart.

It's Halep who usually toys with her opponents, offering a mix of pace and accuracy, but she was the victim this time around as she never quite found her stride on Day 4.

Lucic-Baroni ended Halep's resistance with a match-ending ace.

"Incredible," Lucic-Baroni said. "She's just a great champion and I respect her so much."

"She played well," Halep said. "I couldn't play my best today, but she started to hit the ball very strong at the beginning of the match, and she was better than me today. I just have to go forward."

Halep, who gave way to Sharapova in last year's French Open finale, had been 30-6 for the year before encountering the German-born Lucic-Baroni, who ended a 16-year title drought last year by capturing a championship in Quebec City.

Meanwhile, Sharapova's main focus is to fully recover from her cold after capturing the Italian Open title.

"For me right now it's really about recovery and just being healthy for the next round," said Sharapova, who is trying to become the first player to successfully defend her title in Paris since Justine Henin in 2007.

"Fortunately I played a lot of tennis in the previous two tournaments and this is not a stage where you're trying to fix things or work on things. It's really about maintenance and recovery and getting ready for the next match," she said.

The two-time Roland Garros titlist Sharapova also titled here in 2012. The five-time Grand Slam champion has reached at least the semifinals the last four years in Paris. In addition to her two titles, the tall Russian was the 2013 Roland Garros runner-up to Serena Williams, who also got the best of Sharapova in January's Aussie final.

Next up for Sharapova will be 26th-seeded Aussie Samantha Stosur, who whipped France's Amandine Hesse 6-2, 6-0.

Stosur, fresh off her clay-court title in Strasbourg last week, is a former U.S. Open champion and was the French Open runner-up in 2010.

"Playing Maria is always a big challenge for me," Stosur said. "No matter what surface it's on, I don't have a very good record at all."

In some other Top-10 action, seventh-seeded Serb Ana Ivanovic held off pesky Japanese Misaki Doi 3-6, 6-3, 6-4, eighth-seeded Spaniard Carla Suarez Navarro was leading Virginie Razzano 6-3, 1-0 when the French player retired, and ninth-seeded Russian Ekaterina Makarova snuck past Brazilian Teliana Pereira 6-2, 5-7, 6-3.

The former world No. 1 Ivanovic titled here in 2008 and was the French Open runner-up in 2007. Her third-round opponent will be Croat Donna Vekic.

No. 11 seed Angelique Kerber of Germany eased past Croat Ajla Tomljanovic 6-3, 6-2, while 13th-seeded Lucie Safarova of the Czech Republic drilled Japan's Kurumi Nara 6-2, 6-0.

In other action involving seeds, No. 19 Ukrainian Elina Svitolina overcame Kazakhstan's Yulia Putintseva 1-6, 7-5, 9-7; No. 20 German Sabine Lisicki, a former Wimbledon runner-up, got past Russian Daria Gavrilova, who retired after dropping the first set 6-1; No. 21 Spaniard Garbine Muguruza dismissed Italian Camila Giorgi 6-1, 6-4; No, 28 Italian Flavia Pennetta foiled Slovak Magdalena Rybarikova 6-2, 6-0; and No. 29 French favorite Alize Cornet handled Romanian Alexandra Dulgheru 6-2, 7-5.

Also on Wednesday, German Annika Beck pasted Poland's Paula Kania 6-2, 6-2 and Vekic drubbed Serb Bojana Jovanovski 6-4, 6-3.

On Thursday, the reigning world No. 1 great Williams will face German Anna- Lena Friedsam.

Williams owns two French Open titles among her 19 Grand Slam wins. She currently holds the Aussie and U.S. Open titles and is a sizzling 26-1 this year.

In some other Top-10 play on Day 5, fourth-seeded Wimbledon champ Petra Kvitova will take on Spaniard Silvia Soler-Espinosa, fifth-seeded former world No. 1 and 2014 U.S. Open finalist Caroline Wozniacki will meet German Julia Goerges and 10th-seeded German Andrea Petkovic will battle Spaniard Lourdes Dominguez Lino.

Also seeing action on Thursday will be 16th-seeded rising American Madison Keys and 27th-seeded former No. 1 Victoria Azarenka.