Melbourne - Two of the most exciting young talents in tennis take centre stage at the Australian Open on Friday when 15-year-old American Coco Gauff takes on reigning champion Naomi Osaka.
It will be just the second instalment of a budding rivalry that could light up tennis for the next decade or more, having met for the first time at the US Open last year.
The 38-year-old Serena Williams still reigns over the women's game but Osaka, 22, has been touted as a possible successor in the short term, and Gauff as the longer-term heir apparent.
They have a long way to go to get anywhere near Williams's success and stature, but can press their claims when they meet in the third round in Melbourne.
Williams, chasing a record-equalling 24th Grand Slam title, could await in the quarter-finals.
Williams was hugely impressed by what she saw in Gauff at a pre-season training camp, saying that she was "nowhere near her level at 15 either on the court or off the court, not even close".
Gauff stunned Williams's older sister Venus in the first round on her Grand Slam debut at Wimbledon last year, then pulled off the same trick earlier this week in Melbourne.
She is making her debut at the Australian Open and is the youngest player in the draw.
Japan's two-time Grand Slam champion Osaka, the third seed, will be expected to win because she taught the teenager a harsh lesson nearly five months ago in New York.
On that occasion, the Japanese crushed a tearful and overawed Gauff 6-3, 6-0 in a little over an hour, also in the third round.
But after coming back from a set and 3-0 down to defeat Romania's Sorana Cirstea on Wednesday, Gauff vowed things would be different this time.
"I think I'll be less nervous this time," she told the world's media, displaying remarkable poise for one so young.
"She plays really aggressive. This time coming in I'm going to be more aggressive.
"I think I'm more confident this time around," Gauff added.
'Gauff will be No 1'
Despite that meek defeat last time Gauff still has good memories of playing Osaka, who was defending champion at Flushing Meadows.
Osaka, number one in the world at the time, consoled an emotional Gauff with a hug afterwards.
That was followed by tearful on-court interviews, Osaka asking the teenager to join her with the microphone.
Gauff has not forgotten those gestures and hopes it can inspire the generation even younger than her.
"It was definitely a good moment I think for both of us, especially me," she said.
"But I think more just for the people watching, the little girls watching and little boys who can kind of see what sportsmanship is really.
"I think that's something if I had a child or something, that's something I would want my child to see. It just shows what being a competitor really is," said Gauff.
Justine Henin, the former world number one and a seven-time Grand Slam champion, says that Osaka is the favourite because of her form and experience on the biggest stage.
But the retired Belgian also told Eurosport: "Coco Gauff is one of the players we are going to talk a lot about in the future.
"She has the potential to be world number one, that's for sure."