Johanna Konta suffered a second-successive Fourth Round US Open exit as the Briton lost in straight sets to unseeded Latvian Anastasija Sevastova 6-4, 7-5 in New York.
The world number 14 laboured for most part of a scrappy encounter and was outplayed by her opponent, although was unaided by a rash of unforced errors - 34 in total - on Arthur Ashe Stadium at Flushing Meadows.
Briton favourite versus Sevastova
Konta seeded 13 in the tournament, came into the contest as favourite against the unseeded Latvian. Having dropped just a set in progressing to the last 16 - against Bulgarian Tsevetana Pironkova in Round 2 - Konta toppled both Bethanie Mattek-Sands and Belinda Bencic in impressive straight sets fashion.
Sevastova herself however, had a so-far unblemish record in New York, with straight set victories over Anna Karolina Schmiedlova, Ekaterina Bondarenko and her stunning victory over third seed Garbiñe Muguruza in the Second Round, on Thursday.
In the head-to-record, the two have met just the once, with Konta coming out on top during the Australian Open qualifying match, 6-3, 6-7, 6-4. The Briton was looking to qualify for the last eight of a major slam for the second occasion and her first at Flushing Meadows.
Latvian wins scrappy opener
With Konta winning the toss, the Briton elected to receive and at 0-30 the decision looked a wily one. The Latvian however fought back and took the next six points in a row into the Konta service game, to force the opening break. The 26 year-old opened up a 3-0 lead in the early going.
In contrast, the Brit was labouring and was forced to dig in to prevent the double break at 0-40, having racked up 10 unforced errors in no time. Konta was by now finding her range also and broke back - holding her serve - to level up at 3-3.
Both women were scratching around for consistency in the opener. Sevastova broke again after a wretched eighth game for Konta with three unforced net errors, but the 25 year-old Brit survived a set point to break straight back.
At 4-5 and serving to save the set however, the Konta nerves returned and via some net-cord favour, the Latvian scraped a third break to take the opening set 6-4.
Sevastova capitalizes on Konta errors
With a place in the quarter-finals at stake, Konta went in search of a riposte. Still Sevastova was winning the baseline war of attrition, but the Briton's short game was letting her down also. The duo exchanged early breaks in the second, with Konta staring down the barrel at 1-4 down, just two games from elimination.
The Eastbourne-based player finally held to 2-4 and just as in the opener, Sevastova looked shaky with a lead, as Konta broke to 3-4 but again was struggling to hold her usually rock-solid service game. After more unforced errors, the Brit was broken to 5-3.
With the finish line in sight, the Latvian served out for a place in the last eight, but after having match point, lost her own serve as the match threatened to swing back to the Briton, with Sevastova almost distraught at the change-over.
Konta drew level at 5-5 after inexplicably having saving to a second match point from 40-0, but dug in. Finally the Briton's will was broken with the breaker in sight as - perhaps poetically - Konta was broken for the fourth time in the second set, as Sevastova won out in straight sets 6-4, 7-5.
She will play either Madison Keys or Caroline Wozniacki in the quarter-finals.