Serena Williams had been a vulnerable conqueror at this year's majors, living dangerously and dicing with defeat on numerous occasions as she tried to become only the fourth woman to complete the calendar Grand Slam.
- How Serena's Grand Slam bid was brought to a grinding halt
- Vinci makes rare list in women's tennis after upset win
- Vinci finds it tough to stitch up words after upsetting Serena
On Friday, her luck finally ran out at the US Open, and on a court where she had not been beaten since 2011.
In her 12th three-set contest of the electrifying 2015 run, Williams met her match in Italian doubles expert Roberta Vinci, who ended the American's bid for a share of tennis history with a shocking 2-6, 6-4, 6-4 upset victory in the semi-finals.
Williams, dominating the sport at the ripe old tennis age of 33, had repeated over and over that she felt no pressure in trying to add her name to a list comprised of Maureen Connolly (1953), Margaret Court (1970) and Steffi Graf (1988).
She tried her best to maintain that mantra after her stunning semi-final defeat on an Arthur Ashe Stadium court that had been so kind to her in the past.
"I don't want to talk about how disappointing it is for me," Williams said during a tetchy post-match conference during which she repeatedly refused to answer questions.
"I told you guys I don't feel pressure," she insisted.
"I never felt pressure. I never felt that pressure to win here. I said that from the beginning."
On court, the world number one appeared impatient, flustered and weighed down by expectations against 32-year-old Vinci, over-hitting groundstrokes and second serve returns in an effort to overwhelm and discourage the Italian, who refused to shy away from the daunting challenge.
It was only the third loss in 56 matches for Williams this year and came against an opponent who had never taken a set off her in four previous meetings and was appearing in her first grand slam semi-final.
Despite the defeat, Williams has nothing to be ashamed of after an extraordinary season produced Australian Open, French Open and Wimbledon wins to take her career grand slam total to 21, third on the all-time list behind Court (24) and Graf (22).
Her Wimbledon triumph enabled her to boast possession of all four grand slam titles at the same time for the second "Serena Slam" of her career after first accomplishing the feat when winning the 2003 Australian Open.
Yet Williams had to fight through lapses along the way.
The world number one was extended to three sets twice at the Australian Open, five times at the French Open and twice more at Wimbledon.
She even relied on her champion's survival instincts when she stood two points from defeat against British outsider Heather Watson in the third round at Wimbledon.
But whereas rivals in the calibre of her sister Venus and twice grand slam champion Victoria Azarenka managed to stretch Serena to three sets at the majors, delivering the killer punch seemed to be a feat beyond their capability.
It was left to a 43rd ranked, 300-1 long-shot to show the world that Serena Williams could be beaten.
The Vinci match was the top seed's third three-setter at the U.S. Open and the one that ended an amazing streak of 33 consecutive grand slam match wins.
"I made a couple of tight shots, to be honest, but maybe just about two," she said in what seemed an understatement.
"Other than that, I don't think I was that tight."
The six-time US Open champion uncorked 40 unforced errors, undercutting her 50 winners that included 16 aces.
"I don't think I played that bad. I made more unforced errors than I normally would make, but I think she just played really well," she added.
"She did not want to lose today. Neither did I, incidentally."
