British number one Johanna Konta lost in the US Open first round for the second successive year as she was beaten 6-2 6-2 by Caroline Garcia.
Konta, 27, struggled on serve against the French sixth seed at Flushing Meadows in New York.
Her exit means there are no British women left in the singles draw after Heather Watson’s defeat on Monday.
It is the first time Konta was unseeded at a Grand Slam since the 2016 Australian Open.
Having fallen to 46th in the world rankings this year, she paid the price for a tough draw.
“She played a high level consistently throughout the whole match, made it very difficult for me to get any momentum,” said Konta.
“She showed why she is number six in the world.”
Konta reached a career-high fourth in the world after her memorable run to the Wimbledon semi-finals last year, but struggled to find enthusiasm as she finished 2017 with five defeats in a row – including her surprise US Open defeat by Serbia’s Aleksandra Krunic.
“I’m definitely in a much better place now in terms of the enjoyment that I have of what I do and the motivation I do it with,” she said.
“That has got stronger and stronger as the year has gone on.”
- Wozniacki reaches US Open second round
- Live scores, schedule and results
- Alerts: Get tennis news sent to your phone
Konta outclassed by Murray’s tip
Konta’s slide down the rankings led to a meeting with a player who, as a teenager, was tipped as a future world number one by Britain’s Andy Murray.
Garcia has not managed to reach those heights yet but, having spent over a year inside the top 10, she was too good for Konta in her current form.
Konta, who led Garcia 3-2 in their head-to-head going into the match, was feeling positive after earning impressive wins over former Grand Slam winners Serena Williams, Jelena Ostapenko and Victoria Azarenka on the American hard courts leading up to the US Open.
However, she never looked like causing a problem for the dominant Garcia.
Perhaps Garcia was not the only obstacle for Konta, with a virus forcing her to pull out of the Connecticut Open last week and keeping her bed-ridden for three days.
Despite still sounding bunged up during her pre-tournament interviews on Saturday, she had already started to hit again in New York and insisted she was on the mend and ready to play.
“It was always going to be an accelerated recovery because there’s only so much amount of time. I definitely did the best that I could,” Konta said.
Konta constantly put herself under pressure with a low first-serve percentage, enabling Garcia to dominate and win 48% of Konta’s service points.
Garcia broke twice in each set, although missed another six chances as Konta showed some signs of resistance.
She saved a match point with an accurate serve out wide to force deuce in the final game, but that was brief respite as two loose forehands long saw her lose in one hour and 15 minutes.
“I didn’t have a good serving day, so that definitely hurt me, especially because she was serving well,” Konta added.
BBC tennis correspondent Russell Fuller at Flushing Meadows
Garcia looked every inch a top 10 player. She served superbly, put Konta under constant pressure and did not offer her a single break point.
And so Konta’s Grand Slam singles season ends with just two wins, but this defeat did not feel as dispiriting as her exits from the Australian Open and Roland Garros.
Beating top 10 players has been beyond Konta since last year’s Wimbledon, but she still lies 30th in the annual race.
And with events still to come in Tokyo, Wuhan, Beijing and Moscow, an Australian Open seeding is still very much within reach.