The three most decorated players in Melbourne in the Open era all won in straight sets Tuesday, with Williams starting the roll with a 6-4, 6-1 win in a rematch of last year's final.

She has played her eight times since 2008 and lost the lot, taking just one set along the way.

In the men's competition, No. 3 Roger Federer defeated No. 6 Tomas Berdych, 7-6 (4), 6-2, 6-4, in a quarterfinal match.

Williams, 34, is trying to win her seventh Australian Open and 22nd Grand Slam title.

Federer will be the oldest guy to play in the Australian Open since Colin Dibley in 1979.

Despite the American, who was forced to pull out of the Hopman Cup earlier this month due to a knee injury, calling for the doctor between the sets, she pulled away from Sharapova to seal a straight sets 6-4, 6-1 win.

Radwanska is yet to lose in 2016, but Williams has won the tournament every time she has reached the semi-finals in Melbourne.

Despite winning just two of 21 encounters with Williams, Sharapova is adamant she will remain positive in her search for the key to defeating her nemesis.

French Open champion Wawrinka was the only man to beat top-ranked Novak Djokovic in a Grand Slam match past year - the final at Roland Garros - and the last man to beat him at Melbourne Park after 2010.

Sharapova served a career-best 21 aces against Belinda Bencic in the previous round but failed to penetrate Williams, who broke twice in each set. She was also returning well as the Russian's own serve let her down, with seven double faults.

The 26-year-old Pole jumped out to a 4-0 lead with two breaks of serve in the first set, and while the Spaniard finally managed to hold in the fifth game, Radwanska broke again on her second set point to seal it in 28 minutes.

On a baking hot day in Melbourne, Sharapova made a great start, breaking Williams to 15 before holding with an ace to take a 2-0 lead.

"It's motivating because she's at a different level", Sharapova said.

American tennis player Serena Williams beat out opponent Maria Sharapova to move on to this year's Australian Open semifinals. It was a tight battle and the Russian had two break points herself in the next game, with Williams showing emotion for the first time, screaming "Yes" and pumping her fist as she held on for 5-4.

If Serena's dominance over Radwanska continues - and Williams has never lost in an Australian Open semifinal - her most likely championship final would be against Victoria Azarenka, who is - brace yourself!

"I think that's the reason I am still playing, because I know that I'm capable, if I play well, of being on top".

"She makes you go back to the drawing board, not just for me, but for many other players", Sharapova said.

"I know Aga really well", she said.

Radwanska will play the victor of Tuesday's next match between No. 1 Serena Williams and fifth-seeded Maria Sharapova.

The signs are not good for Radwanska, despite her convincing 6-1, 6-3 win over Spanish 10th seed Carla Suarez on Rod Laver Arena.

"It was tough, we both had our chances", Murray said.