The Williams sisters' relentless run through the Australian Open draw is impressing even record-setting Serena.
Showing no signs of slowing down, 35-year-old Serena and 36-year-old Venus are closing in on a remarkable ninth all-Williams grand slam final - but first since 2009.
Venus has swept into the last four without dropping a set and Serena gets the chance to join her older sister when she takes on in-form Brit Johanna Konta in a quarter-final blockbuster at Melbourne Park on Wednesday.
"In general, people our age aren't really playing at a top level, so indeed it's definitely impressive," the six-times champion said after Venus ousted dual Australian Open junior champion Anastasia Pavlyuchenkova 6-4 7-6 (7-3) on Tuesday.
"She's playing really well. She's been really putting in a lot of the hard work. She had a really intense pre-season. We trained right next to each other.
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"When you put in the hard work, the results, eventually, they show up."
No one in women's tennis has been putting in more hard work than Serena's next opponent, though, and the 22-times major winner knows she too must show up on Wednesday to meet Konta's challenge.
Recognised officially as the WTA Tour's most improved player in 2016, Konta has backed up her breakout season with nine straight wins in 2017, all without conceding a set.
The Sydney-born star's rise up the rankings to ninth in the world began with an unexpected run to last year's Open semi-finals and she'll carry a nine-from-10 record in Melbourne into her first-time meeting with Williams.
The 25-year-old will also carry supreme confidence into her second grand slam quarter-final in 12 months.
"I believe in my own ability. I believe in the good things that I bring to the court and I believe in my ability to fight till the very end," Konta said.
"I have played, over the last year-and-a-half, quite a few grand slam champions and some former world No.1s.
"So I have accumulated. I have prepared myself as much as possible to play a competitor like Serena."
The winner will play either fifth-seeded US Open runner-up Karolina Pliskova or the resurgent Mirjana Lucic-Baroni for a place in Saturday's championship decider.
Venus or fellow American Coco Vandeweghe will clash in Thursday's other semi-final.
