Melbourne, Australia (SportsNetwork.com) - Czech Lucie Hradecka sent shockwaves on the first day of the Australian Open by ousting fifth seed Ana Ivanovic, 1-6, 6-3, 6-2, at Rod Laver Arena.

The Serb Ivanovic, who was the runner-up to Maria Sharapova in 2008, suffered her earliest exit at a Grand Slam event since the French Open in 2011. She was a quarterfinalist here last year.

"I think the whole match I didn't really feel like myself out there," Ivanovic stated. "It was really tough for me to find a rhythm a little bit. In the third set, I really felt like she raised her level."

Hradecka, playing her first Grand Slam main draw since last year's Australian Open, lost in qualifying at other three majors in 2014. The doubles specialist entered the week ranked 142nd in singles play. She has 18 doubles titles, but none in singles.

"In the first set I was so nervous," Hradecka said. "I couldn't hit any balls in the court. When I went outside, I started to serve in the second set, I thought, 'Okay, it cannot be the worst. Let's play every point and let's see what will happen.'"

It's the earliest exit by a top 5 seed since 2003 when then No. 3 Jennifer Capriati was ousted by Marlene Weingartner.

Romanian Simona Halep, the No. 3 seed, topped Italian Karin Knapp, 6-3, 6-2. It's a fresh start for Halep, who began the 2015 season with her ninth career title at Shenzhen, but then withdrew from an event in Sydney due to illness.

Another upset saw Irina-Camelia Begu of Romania beat No. 9 seed Angelique Kerber of Germany, 6-4, 0-6, 6-1.

In other seeded action Monday, No. 21 Peng Shuai of China, beat Germany's Tatjana Maria, 6-4, 7-5; 22nd seeded Czech Karolina Pliskova defeated Evgeniya Rodina, 7-5, 6-1; Belgium's Yanina Wickmayer downed 23rd-seeded Russian Anastasia Pavlyuchenkova, 4-6, 6-3, 6-3; France's Caroline Garcia upset No. 27 seed Svetlana Kuznetsova of Russia, 6-4, 6-2; France's Kristina Mladenovic toppled No. 28 seed Sabine Lisicki of Germany, 4-6, 6-4, 6-2; and Germany's Julia Goerges upended 32nd seed Belinda Bencic of Switzerland, 6-2, 6-1.

Li Na, who has since retired from the WTA, beat Dominika Cibulkova in last year's final at Melbourne Park. Victoria Azarenka had won the previous two finals.