British teenager Emma Raducanu thrashed Spain's Sara Sorribes Tormo to set up a potential US Open last-16 match with top seed Ashleigh Barty.
Raducanu, 18, won 6-0 6-1 against world number 41 Sorribes Tormo as her overseas Grand Slam debut continued with an extraordinary win in New York.
She will face Barty on Monday if the Australian world number one beats Shelby Rogers later on Saturday.
"My game is just getting better with each match," said Raducanu.
After bursting on to the Grand Slam scene with a stunning run to the Wimbledon last 16 as a wildcard, the world number 150 has now matched that breakout display at Flushing Meadows.
Sorribes Tormo is the highest-ranked player Raducanu has beaten in her fledgling professional career.
"I was playing very well and I know Sara is a tough opponent so I had to be on my game and worked so hard," said Raducanu, who won in one hour nine minutes.
"I'm happy I maintained and stayed consistent."
The manner of the teenager's victory was scarcely believable, overwhelming an industrious opponent who has reached a career-high ranking after winning 29 tour matches this year.
Raducanu's power and precision was too much for Sorribes Tormo to handle. The Briton walloped 23 winners and served solidly throughout, too.
Fittingly she sealed victory with another thunderous forehand winner before taking the acclaim of a New York crowd which appears to realise they are watching a star in the making.
"I had to hit through her and hit the corners," said Raducanu, whose number of winners outweighed 16 unforced errors.
"If you trade against her you come second best and I took the game to her and I hit more winners than errors."
Raducanu's star continues to rise
Three months ago, few outside British tennis knew Raducanu. Then she was ranked 361 in the world.
After her stunning run at Wimbledon she became a household name in the UK and is now attracting plenty of attention from the New York crowd, many of whom who wanted selfies and autographs after she beat Sorribes Tormo.
Victory also means the Kent teenager is on the verge of climbing into the world's top 100.
Raducanu qualified for her first major last week and, unfazed by the magnitude of playing in her first overseas Grand Slam, has continued to create a buzz at Flushing Meadows.
In three qualifying matches and three main-draw matches, she has not dropped a set.
"It was an unbelievably impressive performance from such a young player. She has absolutely nothing to lose," former British number one Laura Robson said on BBC Radio 5 Live Sports Extra.
"We kept bigging this match up as a tough opponent - and it is a tough opponent. Sorribes Tormo has won so many matches against top players and has the game to really get you in trouble.
"But she was never in it. She didn't have the chance to play her game because Emma hit her off the court."
Raducanu quickly stamped her authority in the opening stages, breaking 24-year-old Sorribes Tormo's serve at the third attempt in a lengthy second game.
From then on it was one-way traffic as the Briton won 29 of the 42 points played in the first set.
Former British number one Tim Henman called Raducanu's first-set performance "a ball-striking clinic".
She continued to press in the second set, breaking serve at the first opportunity for a 2-0 lead.
With her head in her hands, Sorribes Tormo looks shell-shocked as she trailed 3-0 at the changeover.
Raducanu refused to ease off as she chased a second set to love, maintaining her intensity as the Spaniard battled to get on the scoreboard.
There was a huge cheer as Sorribes Tormo did hold serve for 5-1, after fighting off a match point, but could not further delay the inevitable as Raducanu maintained her composure to serve out a one-sided victory.
"The level was silly," added Robson, who also reached the US Open fourth round as an 18-year-old in 2012.
"A lot of young players can hit the ball hard, but to be this consistent and be able to back yourself is unbelievable."