A historic Hollywood strike robbed the Venice Film Festival of some of its usual glitz as it launched its 80th edition on Wednesday, but a raft of big-name -- and controversial -- directors are keeping the film world buzzing.

The world's longest-running film fest was due to start with "Challengers", a tennis romance with one of the biggest stars of her generation, Zendaya.

But it was replaced at the last minute by an Italian war drama, "Comandante", due to the ongoing strike by Hollywood actors and writers -- primarily over pay and the threat of AI -- that has barred them from publicity work.

The rest of the line-up was largely unaffected and a string of Oscar hopefuls have pressed ahead with Venice premieres, albeit in the absence of acting talent to light up the red carpet.

Emma Stone will not be present for the highly anticipated "Poor Things", in which she plays a Frankenstein-like creature. Nor will Bradley Cooper, who directs and stars in "Maestro" about the legendary conductor and composer Leonard Bernstein.

US media have reported that Adam Driver will show up for "Ferrari". The biopic from director Michael Mann ("Heat") got an exemption from the Screen Actors Guild (SAG-AFTRA) because it was made outside the studio system.

Jessica Chastain is also expected for the premiere of "Memory" towards the end of the festival, according to Variety. It is her first outing since her Oscar-winning turn in "The Eyes of Tammy Faye".

All are competing for the top prize Golden Lion, to be awarded on September 9 by a jury led by Damien Chazelle, director of "La La Land".

Other attention-grabbing entries include Sofia Coppola's "Priscilla", about Elvis Presley's wife, and "The Killer" by David Fincher, who returns to the Lido two decades after "Fight Club" was famously booed at the festival only to become a cult hit in later years.

- Don't understand the 'hostility' -

With less star gossip, a lot of attention risks being absorbed by the inclusion of Woody Allen with "Coup de Chance" (his 50th film and first in French) and Roman Polanski with "The Palace", both in the out-of-competition section.

Allen, 87, was investigated for an alleged assault on his adopted daughter and cleared by police in the 1990s, but that has not been enough for many in the MeToo era, and he has been effectively blackballed by Hollywood.

Festival director Alberto Barbera defended Allen's inclusion, telling AFP: "He has been completely absolved. Twenty-five years have passed and, for me, the hostility towards him, especially in the United States, is absolutely incomprehensible."

Polanski, 90, remains a fugitive from the United States over a conviction for raping a minor in the 1970s. The victim has long since forgiven him, but he faces other assault allegations.

The festival says he is not attending.

Barbera acknowledged it was more complex with Polanski but said: "The history of art is full of artists who were criminals, and we nonetheless continue to admire their work."

There are also out-of-competition premieres for a 40-minute Wes Anderson film, "The Wonderful Story of Henry Sugar", based on a Roald Dahl tale, and a new feature from indie favourite Richard Linklater, "Hit Man".

"The Caine Mutiny Court-Martial", the final film from William Friedkin ("The Exorcist"), who died this month at 87, is also playing out of competition.