Black Caviar heads for quarantine on Sunday with connections of the crack Australian sprinter fully prepared for the fact that she may have run her last race.
The six-year-old just held on to her unbeaten record at Royal Ascot on Saturday when she emerged best from a three-way photo-finish to the Diamond Jubilee Stakes.
She prevailed by a scant head for her 22nd win - but only after jockey Luke Nolen prematurely eased her down in the closing stages.
Thousands of Australians at the course and many more watching in Melbourne's Federation Square held their collective breath as Moonlight Cloud and Restiadargent gained rapidly on Black Caviar in the last 100 metres.
But the winning post came just in time for Nolen, whose frantic late effort to regenerate the mare's momentum illustrated the error of his ways.
It was just as well for the jockey that Black Caviar's neck was fully extended as the combination hit the wire.
Black Caviar's trainer, Peter Moody, was adamant his horse was far from her best in victory. The wear and tear of racing in the highest class may be taking its toll.
In consequence, no thought was given to keeping the mare in Britain for a tilt at the July Cup, an aspiration Black Caviar held in advance of leaving Australia early in June.
"For the last five or six races we have been prepared to accept that it might be her last," Moody said.
"Hopefully that is not the case, but if she is as tired and worn out when she gets home, she may have graced the track for the final time."
The trainer said he could see Black Caviar lacked zest after 400 metres of the 1,200-metre contest.
"I thought she was always in control of the race but she wasn't up on the bridle," he said.
"She never travelled as keenly and strongly as she does at home. She was probably out on her feet 300 metres out. Only her grit and ability got her home.
"Luke (Nolen) was trying to look after her, and while he nearly got caught short, he got the job done."
Nolen, for his part, did not flinch from accepting he had made a mistake that could have plagued the rest of his career.
"Relief is the first emotion I felt," he said.
"It was an error every apprentice is taught not to do, but I got away with it."
"I underestimated how gruelling the 1,200 metre-track is here, but she's got a big neck and she doesn't know how to get beat.
"She is now 22 from 22 and that's what it should be about. It would have been a travesty if she had got beaten. I'd probably have been stabbed."
Nolen shared Moody's suggestion that Black Caviar might be near the end of her tether.
"She wasn't the same horse as usual," he said.
"It has been a 36-hour box-to-box journey from Caulfield (in Sydney) and that must have taken a bit out of her."
Black Cavier will spend two weeks in quarantine in Newmarket, England, before flying back to Australia.
On her arrival Moody will assess her condition before deciding whether to prepare her for a swansong at the Melbourne Spring Carnival, which starts in October.
For sheer elan, her victory could not match that of Frankel, officially rated the world's best racehorse, in the St James's Palace Stakes here on Tuesday.
Nevertheless, she set the seal on what was a vintage Royal Ascot week.
Sir Michael Stoute, who saddled Estimate to win in the royal silks on Friday, added to his haul when sending out Sea Moon for an emphatic victory in the Hardwicke Stakes.
Ryan Moore, who rode Sea Moon, doubled up when winning the meeting's concluding race aboard Simenon - whom he also rode to victory in the Ascot Stakes on opening day.
Simenon's triumph enabled Moore to claim bragging rights as top jockey at the meeting.