Radwanska faces a huge hurdle

Despite the overwhelming odds in Williams' favour, fourth seed Radwanska is upbeat after a 13-match winning streak, including lifting the Shenzhen Open trophy this month.

Agnieszka Radwanska will have to stretch her limits to beat Serena Williams who have never lost a semifinals at the Australian Open.   -  AP

Serena Williams has never lost a semi-final at the Australian Open and has emerged a winner each time she has faced Agnieszka Radwanska, in worrying signs for the Pole ahead of their clash Thursday.

The pair face-off on Rod Laver Arena for a place in the final of the year's opening Grand Slam, with either Germany's Angelique Kerber or British surprise package Johanna Konta awaiting whoever wins.

The imposing American top seed appears invincible after crushing long-time rival Maria Sharapova in the quarter-finals as she steps up her quest to match Steffi Graf's Open-era Grand Slam record of 22 titles.

Her three major wins last year, at the Australian and French Opens and Wimbledon, left her only one short on 21. But Williams, a six-time winner at Melbourne Park, is not getting ahead of herself.

"Nothing's guaranteed in sports. I still have to win two matches against potentially two extremely tough opponents," she said.

Despite the overwhelming odds in Williams' favour, fourth seed Radwanska is upbeat after a 13-match winning streak, including lifting the Shenzhen Open trophy this month.

"I think it's good, especially that I did semi-finals here and I won the tournament (Shenzhen) before," she said of her form. "Couldn't be better so far."

But the 26-year-old, who rarely shows emotion on court, added: "Hopefully I can play my best tennis or I'll be in trouble."

Williams has played Radwanska played eight times since 2008, with the 34-year-old world number one winning the lot.

Another ominous fact facing the Pole is that every time Williams has got past the quarter-finals in Melbourne, she has gone on to win the tournament.

"It will be a good match," said Williams, the defending champion.

"She's been playing really well towards the end of the year, and already this year she's been very consistent. She presents a completely different game, an extremely exciting game.

"So I think it will be a long match and it will be a good match to see where I am."

The two are friends off court and the American said if Radwanska won, she would wish her well.

"I know Aga really well. She's a really nice girl. We always get along," she said.

"Whoever wins, we both deserve to be in the final. If she wins, I'll be very happy for her. I'm sure she'll feel the same way."

The Pole said the experience she gained from making the Wimbledon final in 2012, along with three other major semis, would be crucial.

"Experience is very important in tennis. I'm happy to have that and I'll be ready for the semi," she said.