LOS ANGELES (Reuters) - British rock band Queen, featuring “American Idol” star Adam Lambert as lead vocalist, opened the first hostless Oscars show in 30 years on Sunday with a rollicking performance that brought the Dolby Theatre’s celebrity crowd to its feet.

91st Academy Awards - Oscars Show - Hollywood, Los Angeles, California, U.S., February 24, 2019. Adam Lambert (L) performs with Brian May of Queen. REUTERS/Mike Blake

Queen’s turn at the Academy Awards marked the first time that the U.S. film industry’s highest honors were kicked off by a rock band and set the tone for a telecast punctuated with memorable musical moments and major recording stars.

The two active, surviving musicians from Queen’s original lineup - guitarist Brian May and drummer Roger Taylor - joined Lambert, filling in as frontman for the late Freddie Mercury, to play two of the band’s greatest hits: “We Will Rock You” and “We Are the Champions.”

The familiar guitar and drum riffs brought the star-studded theater audience out of its chairs, with many of the Hollywood luminaries singing along.

It also foreshadowed a big night for “Bohemian Rhapsody,” the hit film about Mercury and Queen that was nominated for best picture. It ended up winning in four other categories, including best actor for Rami Malek’s portrayal of Mercury.

Launching the ABC telecast with a live rock act was an unprecedented choice that came about after comedian Kevin Hart, originally picked to host the show, bowed out because of a furor over past homophobic material in his standup act and tweets.

Hart’s withdrawal in December left the Oscars without a master of ceremonies for the first time since 1989. That year, the broadcast opened with an 11-minute song-and-dance number, widely derided by critics, featuring Rob Lowe and an actress dressed as Snow White.

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In recent years, the opening monologue of the Oscar host has become a platform for gags and jokes lampooning politicians and Hollywood.

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Instead, producers placed greater emphasis this year on musical performances and quick stage cameos by celebrity guests ranging from singer-actresses Barbra Streisand and Jennifer Lopez to tennis champion Serena Williams and U.S. Congressman John Lewis.

Comic actor Keegan-Michael Key was lowered to the stage on fly wires to introduce Bette Midler’s rendition of “The Place Where Lost Things Go,” from the film “Mary Poppins Returns.” Jennifer Hudson performed “I’ll Fight,” from the documentary about Supreme Court Justice Ruth Bader Ginsburg, “RBG.”

And actor-director Bradley Cooper joined his co-star, Lady Gaga, in climbing the steps from the audience to the stage for an intimately rendered duet of “Shallow,” from their film remake of “A Star is Born.” The song, which Gaga co-wrote, won for best original song.

But the opening strains of “We Will Rock You” were perhaps the most riveting musically, a moment as worthy of the Grammys as the Oscars.

Lambert first appeared with Queen’s May and Taylor in 2009 as a contestant on the hit talent show “American Idol” when he performed two of the band’s hits on that program. The trio went on to collaborate occasionally in 2011 and have since toured repeatedly together as Queen + Adam Lambert.

Oscar producers, anxious to boost viewership after a record low U.S. TV audience in 2018, also were under pressure to keep the telecast within its three-hour designated time slot. It ended up running about 20 minutes over.

The Academy of Motion Picture Arts and Sciences was counting on the box office popularity of several of the most nominated films this year - including “Black Panther,” “Bohemian Rhapsody” and “A Star is Born” - to help reinvigorate the show.

Months ago, the academy abandoned an ill-fated plan to create a new category of best “popular” movie as a way of boosting Oscar ratings.

Despite the lack of an official show host, Maya Rudolph got in some jabs as she took the stage with two fellow actress- comedians - Tina Fey and Amy Poehler - to present the night’s first award, to Regina King as best supporting actress for her role in “If Beale Street Could Talk.”

“There is no host tonight, there won’t be a popular movie category, and Mexico is not paying for the wall,” Rudolph deadpanned, skewering the academy as well as U.S. President Donald Trump’s campaign promise to build a southern U.S. border wall at Mexico’s expense.