Shanghai - Defeats for Roger Federer and Novak Djokovic mean that the winner of the Shanghai Masters will be aged 23 or under - more proof that the next generation of men's tennis stars is closing in.
With Rafael Nadal absent from the tournament with a wrist injury, none of the vaunted "Big Three" will win the title on Sunday.
Nobody should be writing the triumvirate off: the 32-year-old Djokovic is number one and the player poised to take top spot off him in the coming weeks is the 33-year-old Nadal.
The 38-year-old Federer is third in the world, while Nadal and Djokovic divvied up all four Grand Slams between them this year.
But in making the last four in Shanghai, Stefanos Tsitsipas, 21, Alexander Zverev, 22, and the 23-year-olds Matteo Berrettini and Daniil Medvedev made a piece of history.
For the first time in 20 years at a Masters 1000 event, all four semi-finalists are 23 and under, according to Shanghai Masters organisers.
"They're knocking on the door big time," Federer said after the 20-time Grand Slam champion was handed a penalty point in a three-set quarter-final loss to Zverev on Friday.
Earlier in the week, before his title assault turned sour, the Swiss said that he had noticed "big improvements" in the performances of the next generation.
"Not like there were none beforehand, but now they are playing with the big boys and really able to challenge us, beat us," he said.
"Having good rivalries also within each other, which I think is important for them to improve as players."
The Greek Tsitsipas dumped out reigning champion Djokovic, who until that point had looked imperious in Shanghai and did not drop a set in winning the Tokyo title last week.
Tsitsipas has now defeated Federer, Nadal and Djokovic in 2019.
In an interview with AFP last month in Zhuhai, southern China, the world number seven gave an insight into the mindset which propelled him to those victories.
Tsitsipas drew accusations of arrogance after saying that he was not prepared simply to tread water and wait for Federer and the others to play themselves into retirement.
"I don't think it's right to wait because you kind of surrender when you wait," he said.
The young Greek made similar comments after turfing the Serb Djokovic out of the quarter-finals in three sets.
"I think be more aggressive because once you get aggressive and they see that you're really going for it, I might even say they get scared," he said.
If that was a bold claim, Tsitsipas also said: "I honestly feel like they are more threatened than I am."
Zverev has long been mentioned as the "next big thing", and even though he has endured a poor season by his standards, the German feels that a generational shift is imminent.
Asked if someone else other than Federer, Nadal or Djokovic can finally win a Grand Slam next year, he said: "I think so, to be honest.
"(Or) maybe in the following year, but in the next two years, I think 100 percent."