It was back in 2003 that Serena Williams first stamped her name on Australian Open history, the then 21-year-old taking down sister Venus to bring home her first title on the blue courts of Melbourne Park.
Fourteen years on, the American is gunning for her 23rd grand slam title, and, at 35, is now among the oldest players left in the draw having fought off 16th seed Czech Barbora Strycova over two sets on Monday.
Venus, at 36 the oldest player in the women's draw, is also through to the last eight in her record 73rd grand slam and Serena pondered whether it was a youthful outlook that had kept the pair at the top of the game for so long.
"I think it's impressive. I think in general people our age aren't really playing at a top level, so it's definitely impressive," she said.
"Venus and I are mentally eight and nine, so that's why we're probably able to play a little better."
The world number two wore down the 30-year-old Czech in muggy, uncomfortable midday heat on Rod Laver Arena in a game that saw her notorious serve come in fits and starts.
Even while Serena conceded the display was "probably not my best day," and that she could "play better," the six-time Australian Open champion has yet to drop a set at the tournament.
Strycova said that, despite the advancing years, Serena was still the dominant force in women's tennis.
"I feel like everything depends on Serena," she said.
"If she has a good day, you don't have a chance. Everything depends on her, what's her day, if she feels well, also if her body feels well. I feel she plays same as before. Yeah, it's tough."
Williams is now the top ranked player left in the draw, after compatriot Coco Vanderweghe made short work of world number one Angelique Kerber on Sunday.
A 23rd grand slam title would vault Williams back to the top of the rankings and next in line to test her mettle against the modern queen of MelbournePark is Britain's Johanna Konta.
The ninth seed, who has never played Williams, was 11-years-old and living in the Sydney suburbs when Serena won her maiden Australian Open title.
"She's one of the players still playing who I looked up to as a young girl wanting to be a tennis professional player," Konta said.
"It's an incredible honour and I will cherish every moment out there."
