Serena Williams is taking nothing for granted against Maria Sharapova in the Australian Open quarter-finals despite her dominant record against the Russian.
Williams has won 17 matches in a row against Sharapova and 18 out of 20 overall, with her last defeat coming 12 years ago in the WTA Championships.
They have met three times in Melbourne where again Williams boasts a perfect record, winning in 2005, 2007 and the final last year.
It means the American, who is gunning for a record-equalling 22nd grand slam title, is hot favourite heading into Tuesday's meeting.
Williams booked her spot in the last eight with a comfortable 6-2 6-1 victory over Russian Margarita Gasparyan and she expects a tough test from her next opponent.
"She always brings something new and something special. She's very consistent, as well," Williams said.
"She knows how to be a player that's always consistently winning and training and working hard and winning matches."
The challenge seemingly for Sharapova is to break through her psychological barrier against Williams.
The world number five has failed even to stretch her opponent in recent contests as 12 of their last 13 match-ups have been settled in straight sets.
A chink of light for Sharapova is that Williams can sometimes struggle under the weight of expectation as shown by her shock exit at last year's US Open when she had been expected to close out a calendar grand slam.
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"I think the person who's winning could definitely feel the pressure because there is a lot of expectations," Williams said.
"The person who is losing, they can feel 'I have lost X amount in a row, I don't have anything to lose'.
"But in this situation, I don't have anything to lose because I'm just here. Every tournament for me is just a bonus at this point in my career."
Sharapova's passage into the quarter-finals was less comfortable as she had to be at her very best to beat talented Swiss Belinda Bencic 7-5 7-5.
The 2008 champion served 21 aces, the most in her career, and hit 58 winners during a display that suggested she may finally be ready to challenge the number one seed.
"It's not like I think about what I can do worse (against Williams), you're always trying to improve," Sharapova said.
"It's only going to be tougher, especially against Serena."
Bencic, meanwhile, departs before the second week of the first grand slam of the year but the 18-year-old proved her potential on Rod Laver Arena.
The Swiss, who is mentored by Martina Hingis, was one of the few players to beat Williams last year but this was her first encounter with Sharapova.
"What surprised me? That her scream is not so loud," Bencic said.
"No, I'm joking. Definitely I was very impressed how she served, probably she's serving the best now in this moment.
"Once she plays Serena it will be ace, ace, ace, everything. It will be an interesting match."
Anna-Lena Friedsam's giant-killing run at the Australian Open ended in tears and injury after a thigh ailment allowed world number four Agnieszka Radwanska to snatch a 6-7 (6) 6-1 7-5 fourth-round win.
The 21-year-old German, who had never been past the second round of a grand slam before this year's tournament, had Radwanska on the ropes when she led 5-2 in the deciding set before injury cruelly struck at 5-4.
The 82nd-ranked German, who beat US Open finalist Roberta Vinci in the third round, then took an injury time-out and had strapping applied to her left leg.
Radwanska held serve, but Friedsam appeared to exacerbate her injury.
The German was given a time warning on the first point of the next game when she was unable to serve and broke into tears. She managed to play on and was 15-40 down when she appeared to strain her right hamstring.
Chair umpire Felix Torralba then sanctioned her again for exceeding the time limit and awarded Radwanska a point that sealed the game and gave her a 6-5 advantage.
The trainer again visited Friedman, who was in constant tears on her chair, but she managed to hobble out and complete the match and was given a massive cheer by the Hisense Arena crowd for her efforts.
Radwanska will now meet either Spain's Carla Suarez-Navarro or Australia's Daria Gavrilova in the last eight.
Meanwhile, Andy Murray's father-in-law Nigel Sears is expected to be released from hospital on Sunday, the Australian Open has confirmed.
Sears, who is the coach of Ana Ivanovic, was in Rod Laver Arena on Saturday evening for the Serb's third-round match against American Madison Keys when he collapsed and had to be carried away on a stretcher.
The 58-year-old remained in Epworth Hospital in Melbourne on Saturday night while he underwent a series of tests but the 58-year-old is expected to be released today.
"My medical advice is that I will be allowed to leave the hospital shortly and I have been cleared to fly back to the UK in the next day or so," Sears said.
