CANNES — Festgoers were singing in the Baz tub Wednesday night as “Moulin Rouge” kickstarted the 54th annual Cannes Intl. Film Festival with high-stepping and plenty of ooh-la-la hoopla.

Cannes cancan dancers lined the steps of the Palais des Festivals, preceding the arrival of helmer Baz Luhrmann, stars Nicole Kidman and Ewan McGregor and a slew of execs — including Rupert and Lachlan Murdoch — from News Corp. and 20th Century Fox, which is distribbing the film.

The audience frequently interrupted the pic to applaud the musical numbers and, in a Cannes rarity, rose at the end to clap rhythmically during the entire six-minute closing credits.

After the show, an enthusiastic Tom Rothman, chairman of 20th Century Fox, admitted a high-profile Cannes launch is a risk for any major studio. “It’s a bold move, but when you see the film, you know why: It’s a bold movie.” He said of the studio’s marketing plan, “We wanted to let the movie do the talking.”

The marathon evening launched with an opening ceremony conducted entirely in French (sort of surprising, considering it’s an international festival; sort of not, since this is France, after all). That was followed by the screening and, in an unusual Cannes move, two post-preem parties: the standard festival-sponsored dinner and a Fox fete that began at midnight.

The dinner was formal, elegant and serious, as 700 diners ate lamb under chandeliers draped with real ivy at Les Ambassadeurs, a huge room in the Palais.

Five minutes and a quantum leap away, Fox erected a re-creation of the Moulin Rouge on the Pantiero, a stretch near the Old Port behind the Palais.

If the dinner reflected the tone of the festival, the party captured the spirit of the film — funky, hip and a little wiggy — as Fatboy Slim spun loud music while 1,000 guests mingled amid tumblers, unicyclists and Apache dancers.

Not that the festival lacked its own touches of gonzo showmanship. The opening ceremony, immediately preceding the film, was launched with a troupe of 10 tap-dancing to “Big Spender,” followed by hostess Charlotte Rampling proclaiming, in French, that film “is life, and an adventure without end.”

Then she introduced jury prexy Liv Ullmann and other members of the jury, and Francis Ford Coppola; after a major photo op, the audience listened to such tunes as “St. Louis Blues” for 20 minutes while they waited for a crew to strike the set and vacuum the stage before the film could begin.

As most of the arrivals climbed the red carpet of the Palais, they were greeted by new fest honchos Thierry Fremaux and Veronique Cayla — with vet topper Gilles Jacob symbolically allowing them to take center stage.

But Jacob emerged to greet the notables in the last few minutes of the arrivals, as the fest jury and filmmakers made their grand entrances.

Among those on hand were producers Tarak Ben Ammar and Elie Samaha, helmer Curtis Hanson, French execs Catherine Tasca and Pierre Lescure and thesps Arielle Dombasle and Andie MacDowell.

The film, which also is in competition, helps set the global tone of the fest: It’s from an American major, with a star and director from Down Under, an international array of actors and pop songs — and, crucially, a French setting.

(Alison James contributed to this report.)