Venus Williams is the oldest women's grand slam semi-finalist in 23 years after edging out Anastasia Pavlyuchenkova in an Australian Open rollercoaster ride on Tuesday.
On a day of milestones, the 36-year-old former world No.1 defeated the Russian 24th seed 6-4 7-6 (7-3) in one hour and 48 minutes to reach the last four in Melbourne for the first time since 2003.
Williams next plays fellow American Coco Vandeweghe after the unseeded giantkiller backed up her fourth-round stoppage of titleholder and world No.1 Angelique Kerber with a 6-4 6-0 quarter-final dispatch of French Open champion Garbine Muguruza.
"I'm just so excited that I have an opportunity to play again on Thursday," Williams said following her 50th singles victory at Melbourne Park.
"I'm so excited. It was such a hard-fought match. She never let up.
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"It's wonderful to be here. I want to go further. I'm not happy just with this, but I'm so happy to have an opportunity to go further.
"It wasn't the easiest start to the year. I had to withdraw from the first tournament and there's so much anxiety that goes with that."
Lining up for her 37th grand slam quarter-final, Venus was giving away 11 years to Pavlyuchenkova.
But it was the two-time Australian Open junior champion who lost her nerve - and serve - at the most critical times.
In a see-sawing opening set, Pavlyuchenkova twice led by a break, only to falter late.
From 4-3 up, the Russian dropped serve twice in a row as 13th seed Williams clubbed a backhand return winner down the line to snatch the set.
The second set was almost a carbon copy, with Pavlyuchenkova again broken from the same end while serving with a 4-3 lead.
The 2006 and 2007 girls' champion in Melbourne, Pavlyuchenkova stood within two points of defeat in the 10th and 12th games of the second set but held firm to force a tiebreaker.
But from 3-1 up in the breaker, the Russian lost six straight points and handed Williams victory with her ninth double-fault on match point.
Venus is the oldest woman to make a grand slam semi-final since legendary compatriot Martina Navratilova at Wimbledon in 1994.
