Lady Gaga paid homage to Frank Sinatra as she cross-dressed in a black suit and slicked back hair to perform at star-studded tribute Sinatra 100: An All-Star Grammy Concert in Las Vegas.
The 29-year-old was among the many performers at this tribute to the late Frank Sinatra to celebrate what would have been his 100th birthday on Wednesday evening.
Channelling androgynous style and a skintight take on the classic white shirt, the pretty blonde took to the stage in a top hat to belt out some of his most famous hits.
Looks familiar: Lady Gaga paid homage to Frank Sinatra as she modelled a black suit and slicked back hair to perform at star-studded tribute Sinatra 100: An All-Star Grammy Concert in Las Vegas on Wednesday
Lady Gaga looked barely recognisable in her ensemble as she took to the stage wearing long flared trousers.
She performed against a backdrop of 20s dancers wearing sequin flapper dresses, with elaborate beaded curtains and sparkly walls.
The provocative performer wore a series of outfits on the night as she wowed the crowds with her range.
This is Vegas after all: The Poker Face singer was surrounded by Vegas showgirls
Top hat: The entertainer gave her chic chapeau a toss in the air and caught it in one fell swoop
Nostalgic: Gaga had people flying to the moon no doubt with her song and dance number
Lean on me: Lady Gaga enjoyed a break backstage with her crooner pal Tony Bennett
That looks comfortable: Lady Gaga squatted down to the floor as she pouted for the cameras
Elaborate: The sets were elaborate and feature Sinatra's name in lights and a black and white image of the late singing legend
Suited and booted: Gaga posed alongside Nancy Sinatra backstage at the event after her performance
Also performing was singer Carrie Underwood, whose provocative show of cleavage was highlighted even more by a sparkling choker that matched a similarly decadent looking belt tied around her slender waist.
The American Idol alum, 32, took to the stage to sing to the starry crowd at the Encore Theater at the Wynn Las Vegas.
Lady Gaga attracted the sight and the light in a one-shoulder gown that blended in well with her cool blonde hairdo.
Sealed with a kiss: The pair looked happy and relaxed as they larked around backstage
Ladies night: Carrie Underwood and Lady Gaga stole more than their fair share of the spotlight at the Sinatra 100: An All-Star Grammy Concert in Las Vegas on Wednesday
Star crowd: The 32-year-old singer showed off more of that royal blue gown with plunging cleavage as she posed with crooner Tony Bennett
Accents: Carrie decorated her décolletage with a sparkly choker that matched her belt
Charmer: The Oklahoma-born star captivated all with her charm as she belted out her hits
Blonde ambition: Carrie wore her light blonde hair in a softly curling way
Black and blue: Katharine McPhee wore a vampy black gown with thigh-baring split
In good company: LL Cool J got to mingle backstage with Carrie
Sheer appeal: Carrie switched into a glamorous and see-through black lace gown
The dress fit her figure loosely and trailed to the tops of her bronze platform shoes.
Long drop earrings dangled from her ears while her make-up was all neutral tones of browns and beiges.
The 29-year-old Poker Face singer got to pose up with her recent collaborator Tony Bennett at the event, which airs on Sunday.
Always a classic: Lady Gaga caught up with her recent collaborator Tony Bennett
Hugs and more hugs: The 29-year-old singer and the 89-year-old crooner were getting along great at the show
Isn't this exciting: Lady Gaga watched the show with a big smile on her face
Big reveal: Alicia Keys certainly wowed in her slinky black gown with cut outs in front
Sexy: Alicia showed off plenty of cleavage as she took to the stage
Mama mia: The performer got to pat Chrissy Teigen's pregnant tum backstage with John Legend
Carrie also did a quick change into another regal formal gown.
Bennett was all smiles as he also posed with Carrie, Alicia Keys and Garth Brooks.
Tony Alicia Keys certainly wowed in a clingy black keyhole gown that showed off her slenderness and her cleavage.
John Legend performed on stage in a white jacket but backstage it was his pregnant wife Chrissy Teigen who swayed the attention.
Thanks for the memories: John Legend performed at the concert with Katharine McPhee
Duet: The singers performed a duet for the star-packed audience
Winning them over: Katharine got into the emotion of the song
Hitting the high notes: Celine Dion performed on stage in a black gown with side split
Sing it out: The Canadian singer lifted her arms up high
Dramatic: Alicia and Celine posed together backstage in their dark and vampy attire
Love and marriage: Adam Levine and his supermodel wife Behati Prinsloo were all smiles
That 'voice': The Voice judge Adam Levine entertained the crowd too
All in the family: Frank's daughter Nancy Sinatra was so touched by all the well-wishers
Chrissy showed off her bump in a glittery gold mini-dress that also put her toned legs on display.
Black was a favoured hue at this glitzy bash worn also by Katharine McPhee and Celine Dion.
While Katharine hit the stage with John Legend, Celine performed a solo number.
Seth MacFarlane was among the performers, and at one point he tried to imitate Sinatra by holding a drink in his hand.
Top hat: Garth Brooks wore his signature hat while singing a song
Spotlight: Garth seemed to really be enjoying his moment in the spotlight
Thumbs up: Tony and Garth had a friendly chat behind-the-scenes
A little bit of country: Trisha Yearwood followed her husband Garth Brooks' example and sang on stage
He's a fan: Arnold Schwarzenegger attended the Sinatra tribute with girlfriend Heather Milligan
Adam Levine brought along his lovely wife, model Behati Prinsloo, who sizzled in a black dress with fury red wrap.
In the audience was Arnold Schwarzenegger and his girlfriend Heather MIlligan.
Nick Jonas strolled on stage in his snowy white dress jacket to sing a song.
Sinatra style: Seth MacFarlane did his best Frank Sinatra impression with drink in hand
Funny face: The multi-talented star had the audience in stitches
Ushering in: Singer Usher sang to the masses while looking suave in a dark suit
Let's get serious: Terminator star Robert Patrick said some kind words about Sinatra
What's so funny: LL Cool J couldn't stop laughing it seemed as he spoke with music producer Quincy Jones
Bright: Nick Jonas showed his bright side in a double breasted white dress jacket
Photobomb: Adam had some photobomb fun in the seats behind Chrissy Teigen and John Legend
The beat goes on: He might be pushing 90 years old but Tony Bennett didn't miss a beat
Taking notes: The 89-year-old singer belted out the notes with no trouble at all
