A Cate Blanchett lesbian love story, a gruelling Auschwitz drama, an all-star tableau on the ravages of age, and a slow-burn martial arts movie from Taiwan all looked well-placed to capture top honours from a jury led by Joel and Ethan Coen.
But in one of the tightest races in years, an Italian ode to a dying mother and the pitch-black comedy “The Lobster” about modern love starring Colin Farrell and Rachel Weisz also seemed within striking distance.
Audiences swooned over “Carol” by US director Todd Haynes, featuring knock-out performances by Blanchett and Rooney Mara as lovers nearly crushed by the conservative values of their time.
It rocketed to the top of critics' “best of” charts after its première last Sunday.
Another revelation from this year's festival was “Son of Saul” by first-time feature director Laszlo Nemes, which takes film-goers inside the gas chambers of Auschwitz in a way never before seen on screen.
Critics hailed the picture for bringing the memory of the Holocaust alive in a visceral way 70 years after the liberation of the camps, as the last survivors enter their twilight years.
“The films that win tend to create a completely realised and self-contained universe. 'Son of Saul' does that,” Vogue reviewer John Powers told AFP.
“The evocation of that universe, the world of Auschwitz, is powerful and exquisitely directed.”
Peter Bradshaw of London's The Guardian newspaper called it “an astonishing debut film” of “extraordinary focus and courage”.
For another frontrunner, Italian Oscar winner Paolo Sorrentino corralled a cast of screen legends including Michael Caine, Harvey Keitel and Jane Fonda in “Youth”, about show-business veterans grappling with fading glory.
Film industry bible Variety hailed the movie as “an emotionally rich contemplation of life's wisdom gained, lost and remembered”.
The picture brought Caine back to the French Riviera festival for the first time in five decades, since the première of his iconic womaniser movie “Alfie”.
“'Alfie' won a prize and I didn't so I never came back,” he joked to reporters.
The art-house crowd also fell hard for “The Assassin” by Taiwanese film-maker Hou Hsiao-Hsien, a glacially paced but stunning tableau of palace intrigue in ninth-century China.
Manohla Dargis of the New York Times said Hou “blew the roof off one of the biggest theatres” in Cannes with “a staggeringly lovely period film” while movie website Indiewire called it “an epic visual poem”.
French daily Liberation and the weekly Les Inrockuptibles both pronounced “The Assassin” their pick for the Palme d'Or.
Meanwhile many viewers were moved to tears by the latest by Italian auteur Nanni Moretti, “My Mother”, about a female filmmaker sent into a tailspin by a career crisis and the loss of a parent.
“It is an extraordinarily elegant film,” French reviewer Philippe Rouyer of Positif magazine, who put it in the top three films this year along with “The Assassin” and Jia Zhang-Ke's triptych of modern China, “Mountains May Depart”.
Moretti's star Margherita Buy could walk off with the best actress trophy, if Blanchett or Mara fail to clinch it.
For best actor, France's Vincent Lindon moved audiences with a stoic performance as an unemployed man fighting to keep his head above water in “The Measure of a Man”, possibly giving “Son of Saul” star Geza Rohrig or Caine and Keitel a run for their money.
With “Macbeth” starring Michael Fassbender and Marion Cotillard in an adaptation of the Shakespeare tragedy still set to screen on Saturday, industry watchers said this year's festival had seen a wild range of quality in the main programme.
“It's not a particularly strong year but not disappointing by any means,” Powers said, predicting a three-way race between “Carol”, “The Assassin” and “The Lobster”.
“No film has really crystallised opinion.”
Last year's Palme d'Or went to the epic drama about Turkey's internal tensions, “Winter Sleep” by Nuri Bilge Ceylan.