ANA Ivanovic admitted preparation was the key to her first career victory over Venus Williams which took her into the semifinal of the Australian Open.

World number three Ivanovic, who became the second of three Serbs into the semi-finals at Melbourne Park alongside Jelena Jankovic and Novak Djokovic in the men's singles, completed a 7- 6 (7/3) 6-4 victory to avenge four previous defeats at the hands of the American.

The 20-year-old will now face Daniela Hantuchova, who defeated Polish 29th seed Agnieszka Radwanska.

I worked very hard in my offseason,'' said Ivanovic, who joined forces with Australian strength and conditioning coach Scott Byrnes prior to Wimbledon in 2006.

I did a lot of stair sprints, sprints up the hills, in a gym, and also a lot of footwork on the court, tennis-specific footwork."

In a first set that featured six breaks of serve in the opening seven games, Ivanovic jumped into an early 2-0 lead before Williams hit back.

A crunching forehand off the Williams serve set up three break points for the Serbian, which she secured when the eighth seed hit a return into the net.

Williams, playing with her thigh heavily strapped, fought back to make it 3-2, and neither player could then hold serve until Williams did so for the first time to level the encounter at 4-4.

The set headed to a tie-break and Ivanovic took control after reeling off five consecutive points, before taking the upper hand in the match when Williams hammered a simplelooking backhand volley into the net.

Williams broke her opponent early in the second set to take a 2-0 lead but Ivanovic broke back on the way to levelling at 3-3.

After slipping to 15-40, Ivanovic battled back and claimed victory when the American hit a forehand well wide.

Afterwards, Ivanovic admitted the victory was particularly sweet against an opponent who had proved so challenging in previous meetings.

I was looking for some revenge,'' she said.

I went out there and from the first moment on I tried to think only on each point. I thought I played some good tennis.'' Williams insists she can still be a force despite not reaching the semi-finals at Melbourne Park for the fifth year in a row.

I have full expectations and aspirations to continue to play high-quality tennis and to continue to be a champion," she said.

Slovakian number nine seed Hantuchova believes a stronger mindset helped propel her into her maiden grand slam semifinal.

Five years after advancing to her last grand slam quarter-final, Hantuchova took the belated next step when she beat Radwanska 6-2 6-2.

Hantuchova said she had previously been too scared to make mistakes and that conservatism was one reason why she had taken so long to reach a grand slam semi-final despite reaching a career-high ranking of five while still a teenager.

I would just get too hard on myself and was not able to forgive my mistakes,'' said the 24- year-old.

I just realised that things are not always going to go your way, and sometimes you have to work for them.

It's the same in life. You have to get through some difficult times.'' There were few difficulties for Hantuchova against Radwanska, though, who could show only glimpses of the form that had accounted for second seed Svetlana Kuznetsova and 14th seed Nadia Petrova.