Greece's Tsitsipas battled back from 3-5 down in the third set to eliminate Medvedev with a 6-3, 6-7(11), 7-6(1) win to set up a showdown on Friday with Rublev for the Red Group's other semi-final spot.
Copil, the World No 93, stunned second seed Alexander Zverev of Germany 6-3, 6-7 (6), 6-4 in the day's other semi-final.
A 55-shot, marathon rally brought fans to their feet in Flushing Meadows on Friday but nearly leveled the two men who lived through it, Norwegian Casper Ruud and Russian Karen Khachanov, competing in their US Open semi-final.
Carlos Alcaraz swatted aside a swarm of bees and world number six Alexander Zverev to reach the semi-finals at Indian Wells.
"I'm just devastated obviously," Kyrgios told reporters
Tennis matches at the Ariake Tennis Park will begin from 3pm local time (0600 GMT) from Thursday, governing body International Tennis Federation said after requests from players who had struggled in the stifling weather.
American teenage sensation Coco Gauff became the youngest player to win a WTA title in 15 years as she beat former French Open champion Jelena Ostapenko in the Linz Open final on Sunday.
Images from Day 10 of the 2021 French Open at Roland Garros in Paris on Tuesday.
Becomes only third Indian to win a singles match at the Games.
World number one Carlos Alcaraz will not play in the Australian Open after picking up a right leg muscle injury during pre-season training, the Spaniard said on Friday.
Djokovic had been favourite to win a 10th title at Melbourne Park and claim a 21st Grand Slam crown but the Serb now faces being deported from Australia.
Rafael Nadal has not played a competitive match since bowing out in the second round of this year's Australian Open.
Nadal was much more than a claycourt bully, though. He spent more than 900 successive weeks from 2005 in the ATP's top 10, 209 of them at number one and at the age of 24 became the youngest player to complete the career Grand Slam.
The trio have dominated men's tennis over the last 20 years and played a major role in shaping the direction of the sport
Fans are buzzing over the prospect of a rematch between world number one Alcaraz and second seed Djokovic in a potential New York finale
Yuki Bhambri is in line to win his second Challenger level singles title of the season as he advanced to the summit clash after his opponent withdrew due to a lower back problem in Shanghai.
Images from Day 7 of the 2025 Australian Open at Melbourne Park on Saturday.
Three-time US Open champion Djokovic, who comes into the tournament having won his fifth Wimbledon title, is followed in the seedings by 2017 winner Rafael Nadal.
Images from Day 7 of the 2024 Australian Open in Melbourne on Saturday.
'I'm just glad to overcome today's challenge in straight sets and move on.'
Rafael Nadal is the oldest title winner in the history of the clay-court tournament.
Here is a quick glance of all the highs and lows from Nadal's stupendous career:
Here are a few famous faces that watched Nadal go one step close to matching Roger Federer's 20 Grand Slam titles...
Djokovic was soundly beaten by Zverev in the 2018 final, a match played out in an electrifying atmosphere in front of 18,000 fans. This time the arena was empty because of the COVID-19 lockdown, a surreal backdrop for a match with so much riding on it for both men.
Second seed Daniil Medvedev will launch his bid to win his first major title against veteran Frenchman Richard Gasquet.
World number two Novak Djokovic has withdrawn from the BNP Paribas Open in Indian Wells, the tournament announced on Wednesday, in the latest setback for the player due to his refusal to take the COVID-19 vaccine.
Tsitsipas had lost all five previous matches against the Russian, but turned the tables in impressive fashion.
Carlos Alcaraz moved to within two wins of completing the 'Sunshine Double'
Nadal pulled off his greatest escape to deny Daniil Medvedev again, less than three years after leaving the Russian heartbroken in five sets at the 2019 US Open final.
With Rafael Nadal out with injury, can Novak Djokovic go past the Spaniard and pick up a record 23rd Grand Slam title.
Andy Murray saved five match points to defeat Jiri Lehecka at the Qatar Open on Friday and reach a first ATP Tour final since June last year.
'Let's be confident, let's be positive and let's see what's going on'
Nadal arrived in Paris with his own doctor to get through the tournament despite the injury.
Pole says she feels much better prepared to handle the pressure of her latest career milestone.
He was drawn in the toughest half of the draw with Nadal as well as in-form Spanish teenager Carlos Alcaraz and world number three Alexander Zverev, who could clash in the last eight.
Certainly the prospect of another showdown at the US Open in a few weeks is exciting, but whether or not 23-time Grand Slam champion Djokovic can stretch his career long enough to battle Carlos Alcaraz on a regular basis is questionable.
With Sunday's win, the world number one took his Grand Slam tally to 18, just two shy of Roger Federer and Rafael Nadal's men's record of 20.
Images from Day 5 of the 2022 French Open at Roland Garros in Paris on Thursday.
This year's US Open runs from Aug. 28-Sept. 10.
Novak Djokovic is capable of extending his record for holding the men's World No. 1 ranking for most weeks to 400, said Russia's Daniil Medvedev who will climb up to a career-best ranking of second on Monday.
