Ana Ivanovic has admitted that she felt "a little bit lost" on the court after suffering a shock defeat to qualifier Lucie Hradecka in the first round of the Australian Open.

Despite a fine start from the fifth seed, it was Hradecka who progressed with a 1-6 6-3 6-2 triumph, and Ivanovic struggled to offer an explanation for her poor form in Melbourne.

"I think, the whole match, I didn't really feel like myself out there," the 2008 finalist told reporters. "It was really tough for me to find rhythm a little bit. In the third set it really felt like she raised her level. I really today struggled to find rhythm. Just a little bit lost.

"It was really, I think, all around the game. That made a big difference. I really felt like I couldn't really put so much power on my serve or the groundstrokes. So many times my forehand was finishing short as well, and that was very disappointing. In Brisbane my serve was on such a good level. I really felt like I improved in the off-season. Obviously today was really not working."

Hradecka, who is currently ranked 142nd in the world, has now reached the second round of the Australian Open in each of the last four years.