British sensation Emma Raducanu will face Leylah Fernandez in an all-teenage US Open final at Flushing Meadows.
The 18-year-old defeated No 17 seed Maria Sakkari 6-1, 6-4, to become the first player - male or female - in the professional era to reach a Grand Slam final after coming through qualifying.
She will play Leylah Fernandez, who turned 19 on Monday, after the Canadian edged out second seed Aryna Sabalenka 7-6, 4-6, 6-4.
If Raducanu wins in New York on Saturday, she will be the youngest Grand Slam champion since Maria Sharapova triumphed at Wimbledon in 2004 aged 17.
It has been a remarkable tournament for Raducanu has not lost a set en route to the final and has dropped just 27 games in her six matches.
Tearing up the record books, Raducanu is also now the first British woman to reach a major final since Virginia Wade won Wimbledon in 1977.
Two months after bursting on to the scene at Wimbledon ranked 361st in the world, a month after receiving her A level results, and 13 days after entering qualifying in New York, she stands on the brink of a stunning sporting achievement.
Raducanu said on court: “Honestly the time here in New York has gone so fast. I’ve just been taking care of each day and three weeks later I’m in final. I can’t actually believe it.
“Today I wasn’t thinking about anyone else except for myself. While I have the moment I want to thank my team and the LTA and everyone at home for all their support.
“Since I’ve been here from the first round of the quallies I’ve had unbelievable support.”
As for her chances in the final? “Is there any expectation? I’m a qualifier so technically there’s no pressure on me,” she added.
The first set lasted just 36 minutes as Raducanu blew away her 26-year-old Greek opponent before being made to work in the second.
An early break kept Sakkari at bay and only an extraordinary rally at break point prevented Raducanu from taking a 5-2 lead.
Two service holds and a delicious volley on match point later and Raducanu had completed the latest stride in her improbable march towards sporting immortality.
Fernandez's own storybook tournament continued with yet another upset on Thursday.
Rankings-wise, the second seeded Belarusian represented the toughest challenge yet for the 19-year-old left-hander but with a string of big-name victims behind her Fernandez had already shown she could not be intimidated.
The Canadian has stated she could beat anyone and backed up the bravado with victories over four-time Grand Slam winner and defending champion Naomi Osaka in the third round, three-time Grand Slam champion Angelique Kerber in the fourth and fifth seed Elina Svitolina in the quarter-finals.
One of the game's big servers Sabalenka threw everything she had at Fernandez, including 10 aces, but had no better luck against the youngster, who played with veteran poise throughout the three-set thriller.
“Impossible is nothing,” said Fernandez. “Like my dad would tell me all the time, there's no limit to my potential, to what I can do.
“Every day we just got to keep working hard, we got to keep going for it. There's no limit to what I can do.”
Ranked No 73 in the world at the start of the US Open, getting to the Grand Slam final would have been considered Mission Impossible by many, but on Saturday, Fernandez will take on Raducanu in an all-teenage final no one could have predicted before the tournament.
It will mark the eighth time a Grand Slam final in the Open era will be contested by two teenagers, and the first since the 1999 US Open between Serena Williams and Martina Hingis.