Novak Djokovic broke down in tears during a US Open first-round defeat by Argentina's Mariano Navone which provided further evidence age is fast catching up with the 39-year-old great.
The 24-time Grand Slam champion was overcome by emotion in the deciding set of a dramatic match where he struggled physically throughout and had to vomit into a towel bin.
Djokovic, seeded fourth, showed the fight for which he has always been renowned before succumbing to a 7-6 (7-5) 5-7 4-6 6-2 6-1 loss in a humid New York.
It was the first time the Serb had been beaten in the opening round at Flushing Meadows and the first time he had lost in the opening round of a Grand Slam tournament since 2006.
"I think it was obvious that it was an awful feeling on the court for me," Djokovic said.
"I don't want to take too much out of Mariano's win. Congrats to him, he's a nice guy and a fighter - but I didn't enjoy myself."
Djokovic managed to raise a smile as he congratulated 25-year-old Navone on what will rank as one of the biggest victories of the world number 49's career.
But, after showing grace and class while congratulating his opponent, a disconsolate Djokovic was unable to keep a brave face for long and appeared close to tears again as he trudged back to the locker room.
The defeat ended Djokovic's latest bid for a standalone record 25th Grand Slam singles title, which would move him clear of Australia's Margaret Court.
Djokovic had reached at least the semi-finals at six of the previous seven Grand Slams going into the US Open, but the manner in which he struggled in the humid conditions was a worrying sight for his supporters.
Djokovic looked nauseous throughout a tense encounter and he appeared to be dealing with a similar issue to the one which affected him at the Cincinnati Open two weeks ago.
In his only appearance on the North American hard courts before heading to New York, Djokovic wilted in similarly humid conditions in a shock early exit to Argentina's Thiago Tirante.
Afterwards Djokovic revealed he had been hampered by a "health condition" which has been "bothering" him in oppressive conditions over a number of years and, discussing the issue with reporters shortly after losing to Navone, called it a "serious issue".
"It's something that I have been carrying pretty much every match this year - vomiting, throwing up," Djokovic said.
"And then my whole body starts to collapse basically, cramping and pain - the back just gave up in the end and shoulder, and I couldn't close it out."
BBC