Boundaries, ceilings and most definitely age have never meant much to the Williams name when it comes to women's tennis.
The elder of the sport's most famous sisters yesterday gave the world another reminder of just how capable she remains of rewriting history - and she could yet do so again today, when she plays "good friend" Caroline Wozniacki in the final of the BNP Paribas WTA Finals Singapore presented by SC Global.
At 37, Venus Williams is already the oldest player to reach this stage of the Tour's prestigious season finale. The American breaks the previous record held by another great: Martina Navratilova, who was 36 when she lost to Monica Seles in the 1992 final.
Should Venus lift the Billie Jean King trophy tonight at the Singapore Indoor Stadium, she would easily surpass the previous oldest champion - younger sister Serena, who holds the current mark for winning in 2014, also in Singapore, as a 33-year-old.
On paper, with a dominant 7-0 head-to-head record over Wozniacki - dropping just a single set in the process - Venus looks a good bet to claim that accolade from her sibling.
Few would dispute Venus' ability to outgrind players younger than her, even in the twilight of her long and storied career.
The world No. 5's 6-7 (3-7), 6-2, 6-3 comeback victory over Frenchwoman Caroline Garcia in their semi-final last night was noteworthy, especially against a gritty opponent who has won nine of her last 10 three-set matches.
Even fewer would doubt the veteran's mental fortitude, given her incredible return to the peak of the sport with a 2017 season that included two Grand Slam finals. It comes after she was diagnosed with Sjogren's Syndrome in 2011, an autoimmune disease that causes fatigue.
"It's hard to produce your best tennis at the end of the year. To be standing in the winner's circle - almost - is amazing," Venus said on court last night to a largely partisan crowd, several of whom had showed up with posters supporting "Queen Vee".
Her one-sided track record against Wozniacki aside, the American will still need to produce her best game today, given the form her world No. 6 opponent has shown in Singapore.
The Dane took out big-serving Czech Karolina Pliskova in their semi-final, winning 7-6 (11-9), 6-3.
The match included a long-drawn first set. Wozniacki had been up 6-1 in the tie-breaker, squandering five set points and saving six set points herself before she succeeded in claiming the set at the sixth time of asking.
The slow surface of the court this week has favoured her trademark defence and her effective counter-punching.
She is making a first return to the final of the season finale since she finished runner-up to Kim Clijsters in 2010. This is her eighth final this year.
"Well, Venus, I have had a tough match-up against her in the past, but I haven't played her in a while," said Wozniacki, who last played the American at the 2015 Miami Open.
"It would be really tough. She's had a great year. She hasn't played many tournaments, but the tournaments that she's played, she's done really well in."
Said Venus: "(Caroline) is playing well. I haven't played her in ages. I have to gauge how it goes and try to figure out the solution.
"At this level I think we've both improved our game. You have to, to stay on tour. So I will see what she's doing, see what's working."
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Singles final: StarHub Ch203, 7.30pm