Not since legendary Irish trainer Vincent O'Brien saddled Alleged to victory in 1978 has any horse secured a repeat success in Europe's richest race.
Criquette Head-Maarek's filly was installed as a firm favourite to join those hallowed ranks immediately after romping home by five lengths with a sensational display at Longchamp 12 months ago.
However, this season has not gone according to plan for the four-year-old daughter of Epsom Derby hero Motivator and she has plenty to prove.
A narrow defeat to tough-as-teak veteran Cirrus Des Aigles over a shorter trip in April's Prix Ganay was not a concern, but Treve then suffered injury when third at Royal Ascot.
During a three-month absence, her Qatar-based owners Al Shaqab Racing's retained rider Frankie Dettori was replaced by last year's Arc jockey Thierry Jarnet, though that could not inspire a return to form.
The filly's trademark finishing speed was again missing in the Prix Vermeille on Treve's comeback, but Head-Maarek declared: "I really do believe she has come on for her latest run.
"I'm convinced she has recovered a big part of her powers and that is very encouraging as we approach the big day.
"The objective has always been to make her a double Arc winner and a lot of hard work has gone in to achieving that aim."
Heading the list of this year's rivals is impressive Epsom Oaks and Ascot King George winner Taghrooda, trained in Newmarket by John Gosden.
This three-year-old filly suffered a surprise defeat against Tapestry in the Yorkshire Oaks but had excuses for that loss and jockey Paul Hanagan has high hopes of getting back to winning ways.
He revealed: "There was a bit of a blip at York, but she was just coming into season then, so I think she's got every right to head the market. She won't shy away from anything and I'm really excited."
With more than £4million in prize money up for grabs overall and just short of £2.4m going to the winner, it is no wonder the Arc attracts entries from all over the world.
Japanese visitors have been runner-up four times, including Orfevre in the last two renewals, and three more leading contenders have travelled across from that country again this term.
Just A Way will be bidding for a fifth straight victory and showed he can handle a long journey when winning the Dubai Duty Free at Meydan in March, Gold Ship is a former 2,000 Guineas and St Leger winner back at home and three-year-old filly Harp Star edged him out at Sapporo last time.
Bookmakers rate Ectot the best hope of a third straight French success following his Prix Niel triumph on trials day, while unbeaten filly Avenir Certain is another big local fancy.
Irish trainer Aidan O'Brien sends over 2013 Epsom Derby star Ruler Of The World, €6m purchase Chicquita and Tapestry, who was supplemented late on at a cost of €120,000.