Novak Djokovic's bid to become the first man to complete the Golden Slam lay in tatters on Friday after he was toppled by Germany's Alexander Zverev in the singles semi-finals at the Tokyo Games.
Zverev fought back from a set and a break down to pull off a staggering 1-6 6-3 6-1 win over the Serbian world number one to set up a final showdown with Karen Khachanov of the Russian Olympic Committee (ROC).
Fifth-ranked Zverev is the first German man to make an Olympic final since Tommy Haas won silver at the Sydney Games in 2000.
Djokovic had arrived in Tokyo gunning for the Golden Slam -- winning all four majors and Olympic gold in the same year -- after triumphing at the Australian Open, Roland Garros and Wimbledon in 2021. The US Open begins next month.
Victory in Tokyo would also have secured the 34-year-old Djokovic the only major honour still missing from his collection -- an Olympic gold medal.
But the 2008 Beijing Games bronze medallist lost that chance after Zverev secured the win with a crushing backhand down the line winner.
A later defeat in the mixed doubles semi-final with partner Nina Stojanovic rubbed salt in the wound, as the Serbian pair fell 7-6(4) 7-5 to the ROC's Elena Vesnina and Aslan Karatsev.
"Tough day man, really tough day," a visibly upset Djokovic told reporters.
"I feel so terrible right now, can't be positive right now."
Djokovic could still go home with two bronze medals on Saturday, with the Serbian set to meet Spain's Pablo Carreno Busta in the men's singles and Australian pair Ash Barty and John Peers in the mixed doubles partnering Stojanovic.
Emotional Zverev
In Friday's semi-final, an emotional Zverev embraced his opponent at the net, telling Djokovic "I'm sorry".
Alexander Zverev of Germany reacts after winning his semifinal match against Novak Djokovic of Serbia — Reuters photo
"I told him that he's the greatest of all time," the 24-year-old told reporters.
"But in these kind of moments, we're very close and we're good with each other, so of course, I'm happy that I won but at the end of the day I also know how he feels."
Earlier on Friday, Khachanov outgunned Spaniard Carreno Busta 6-3 6-3, capping a memorable summer for the 25-year-old, who made the Wimbledon quarter-finals this month.
"I play tennis for those moments, I practise for these kind of matches and when you get there, when it's paying off, it's just a pure pleasure to be here...," the 25th-ranked Khachanov said.
"(They are) the kind of memories that will stay forever."
In the men's doubles, Croatia's Nikola Mektic and Mate Pavic beat compatriots Marin Cilic and Ivan Dodig 6-4 3-6 (10-6) for their country's first ever gold and silver medals in the sport.
New Zealand claimed their first Olympic tennis medal, as Marcus Daniell and Michael Venus took home the bronze following a 7-6(3) 6-2 win over Americans Tennys Sandgren and Austin Krajicek.
The ROC's Vesnina and Karatsev will face compatriots Anastasia Pavlyuchenkova and Andrey Rublev, who beat Barty and Peers, in the mixed doubles final on Sunday.