Czech world No.2 Petra Kvitova admits she failed to seize the moment in her Australian Open semi-final loss to Maria Sharapova, as the chance to mount an assault on the No.1 ranking again slipped away.

For the 21-year-old reigning Wimbledon champion, Thursday’s defeat had a familiar feel.

As in her semi-final defeat to China’s Li Na in her preceding tournament, the Sydney International, the Czech left-hander looked a likely winner at stages of the match.

Against Li, she was up a set and a break before fading away.

Against Sharapova, she was up a break of serve early in the deciding set and, after giving up that advantage, had 0-30 on Sharapova’s serve at 4-4, with only a successful challenge by the Russian preventing the scoreline reaching 0-40.

But it was Sharapova who found her best tennis when it counted, while Kvitova’s standard slipped badly as she gave up serve in the final game to fall to defeat.

“I had a lot of chances to break her,” Kvitova said.

“I didn’t do it, and it was really tough to concentrate on my serve.

“I know that all games in the third set I served very well, and then was a game that I didn’t really have like first serves or something, and she returned very well in this game.

“It was unfortunate for me.

“She played some break points very well, but I could have been more aggressive and more (gone) for the winners and not only waiting, waiting (for) what she can do.”

Had Kvitova won the Sydney International, she would have come to Melbourne as the world No.1.

She also would have claimed that status had she downed Sharapova and gone on to win Saturday night’s final.

Instead, she will slip from her career-high No.2 to No.3 next Monday.

Sharapova and fellow finalist Victoria Azarenka will occupy the top two spots, with the order to be determined by the result of the final.