Johanna Konta is the British No 1 and the World No 7 and, in the absence of Andy Murray, was carrying the hopes of a nation on her shoulders at the last Grand Slam of the year.
She also had a stab at becoming the World No 1 but was tripped up at the outset by a rank outsider.
She said she felt on top form going into the US Open as she made her bid for a maiden Grand Slam title, and many felt she could make the distance but nobody factored Aleksandra Krunic in the script.
Konta returned to the scene of her breakout appearance as a genuine contender for the title but had to clear the first hurdle and failed.
The 26-year-old burst into the public’s consciousness in 2015 when she came through qualifying to beat Garbiñe Muguruza and Andrea Petkovic on her way to the fourth round.
She then repeated that run last year, but after reaching the semi-finals at Wimbledon in June, Konta is one of eight women who could end the tournament on top of the world rankings.
She matched her best ever performance in a major with a semi-final appearance at Wimbledon earlier in the summer and heads to New York in confident mood.
As the US Open is the final major of the year, there are often concerns over fatigue for many players at Flushing Meadows but Konta says she is fully prepared for the task in hand.
“I feel pretty good,” she said, as reported by The Scotsman.
“I feel excited. I’m still very clear and comfortable with how I am on the court. Physically, mentally, emotionally I am pretty good.”
It did not come together for her on the day though as Konta took on the Serbian No 78 Krunic in the first round on Monday, when the confidence at first brimmed and then faded.
Krunic, who was born in Moscow but represents Serbia, enjoyed her best Grand Slam run in the 2014 US Open when she beat third seed Petra Kvitova on her way to the fourth round.
That 6-4 6-4 win three years ago was the 24-year-old’s only success over a top-10 player and she is yet to crack the top 50 of the women’s game but she proved to be more than handful for Konta, who was made to fight.
She has done little of note since but is a fearless ball striker and a player who can take advantage of a big name having a bad day.
No-one gave her much hope but on a day when nothing came easily for the Brit, as she struggled with her serve and her footwork in the face of the Serbian challenge, Krunic’s obvious talent blossomed and her confidence grew.
Konta took the first tight set but then dropped the second, and quickly went down a break in the third.
She endured in front of the growing crowd on the Grandstand court, earning herself a break back to level at 2-all and the shriek she uttered as she secured a 3-2 lead in the decider, said everything about the tension she was feeling.
The unforced error count, however, grew for the Brit as the confidence faded in the face of Crunch’s persistence.
She never looked comfortable against Krunic and lost 4-6 6-3 6-4 in two hours and 17 minutes.
It was simply a bad day at the office for Konta as her serve failed her and she suffered the shock defeat at the hands of the unseeded Serbian with dignity and, no doubt, disappointment.
The collapse of the World No 7 in the first round narrows the group looking to become the World No 1 from eight to seven on a day that proved disappointing for British women’s tennis in New York, after Heather Watson also suffered defeat, 6-4 6-4, at the hands of Alize Cornet.
Such is this sport when, on Day 1, two other seeds also fell – Laura Davis (32) at the hands of Sofia Kenin, 7-5 7-5: and Kiki Bertens (24) losing to Maria Sakkari, 6-3 6-4 – but none so dramatically as Johanna Konta, who will rue her loss of form when it really mattered most.