Spanish top seed Carlos Alcaraz moved into the Wimbledon semi-finals for the first time and will face Russian third seed Daniil Medvedev in the last four.
Alcaraz beat Danish sixth seed Holger Rune, another 20-year-old, 7-6 (7-3) 6-4 6-4 in his quarter-final.
Unseeded Chris Eubanks’ dream run was ended by 27-year-old Medvedev in a thrilling five-set contest.
Medvedev, who had never been past the last 16 before, beat the American 6-4 1-6 4-6 7-6 (7-4) 6-1.
Now Alcaraz and Medvedev – who have both won major titles on the US Open hard courts – will attempt to reach their first finals on the Wimbledon grass when they play in the last four on Friday.
In the other semi-final, Serbian second seed Novak Djokovic, who is going for a record-equalling eighth men’s title, faces Italian eighth seed Jannik Sinner.
Reaching the semi-finals is a dream – Alcaraz
Alcaraz and Rune are seen as two of the hottest prospects in the men’s game, with expectations increasing they can build an exciting rivalry in the coming years.
Alcaraz was born only a week after Rune in 2003 but is clearly further ahead in his development, having already claimed the world number one ranking and a maiden Grand Slam title.
With a dominant performance in his first Wimbledon quarter-final, the prodigious Spaniard again proved his time is already here.
It is easy to forget Alcaraz is playing in only his fourth senior tournament on grass, such is the speed and quality with which the Queen’s champion has adapted this summer.
“For me, it is a dream to be able to play a semi-final here. I think I am playing great, a good level. On this surface, it is crazy,” he said.
Rune’s development on the grass has also been rapid. He had never won a professional match on the surface until this summer, but it was hoped he could push Alcaraz in an eagerly anticipated encounter.
Rune earned an early break point, which Alcaraz saved with an ace, but further opportunities were scarce.
Alcaraz applied pressure when the Dane twice served to stay in the set, but he held on to tee up a tie-break as the tension continued on Centre Court.
Nobody could confidently predict which way the set decider would go.
But a double fault from Rune at 3-3 handed over the momentum, allowing Alcaraz to take control and unleash a visceral roar when he sealed the advantage with a ripper of a backhand winner.
Another tight set followed with little to choose between the pair. Another mistake from Rune proved fatal.
A smash into the net brought up break point – and groans from an invested crowd – and Alcaraz took it with a crisp backhand down the line.
Rune popped off court for a mental reset and it seemed to work as he confidently held to love at the start of the third set.
But he was given a time violation for taking too long to serve at 2-2, contributing to Alcaraz breaking and the set running away from him.
Alcaraz was unable to take a match point when Rune served at 5-3 but came through a minor wobble in the next game to become the youngest Wimbledon men’s semi-finalist since Djokovic in 2007.
“I feel like whoever got that first set had a big advantage,” said Rune, who added he did not feel well when he woke up on Wednesday morning.
“I did my best in the circumstances. I fought until the end. He played a good match, I could have played better. It’s a part of it and I just have to move on.”
Medvedev reaches first Wimbledon semi-final
When Medvedev faces Alcaraz it will be the first time the Russian has featured in a Wimbledon semi-final and the fourth time he has made this stage at a Grand Slam tournament.
With the decision made to keep the roof closed on Court One, a cacophony of noise was generated with the sound of the ball hammering off racquets and cheers from the crowd echoing around the arena.
On his debut in the Wimbledon main draw, big-hitting Eubanks was featuring in a first Grand Slam quarter-final and had the backing of the British crowd.
The world number 43 has endeared himself to the All England Club crowds by bringing his style and personality to the grass courts, despite having claimed it is the “stupidest surface” earlier this summer.
Medvedev took a comfortable first set but Eubanks’ powerful shots from the baseline and rapid serving quickly wrapped up the next two to give him the lead.
The Russian stuck to his game plan in the fourth set and relied on the notion that he could maintain his level for the long run.
That plan worked as Eubanks faded away in the deciding set, falling a double-break behind and ultimately succumbing after sending a forehand long.
Medvedev has never lost on Court One and his greater experience in latter stages of tournaments proved too much for the underdog.
But Eubanks will reflect on a stunning grass-court swing, where he won a first ATP title and will rise into the world’s top 40 having never previously cracked the top 100 until April.