Ana Ivanovic on Tuesday said the thrill of beating Serena Williams left her "emotionally drained" in her Australian Open quarterfinal loss to Eugenie Bouchard - but she still believes she is playing the best tennis of her life.

The Serb, who won the Auckland International en route to Melbourne Park, could not keep her win streak going against the emerging Canadian teen, who won 5-7, 7-5, 6-2 to set up a last-four clash with Li Na.

But the former world No 1 said she was encouraged by her early season resurgence and was eyeing a return to the top 10 after struggling to hit the big time since winning the 2008 French Open.