Beyoncé turned 42 in style with a surprise serenade from Diana Ross on Monday.

Ross, 75, made a surprise appearance at the singer's Renaissance World Tour in Los Angeles on Monday to sing "Happy Birthday."

Stepping out in a sparkling black and feather gown, the Motown legend drew huge cheers from the crowd as she led them in singing "Happy Birthday" to the shocked “Cuff It” singer, with Ross saying she had to repay the favor after Beyoncé once sang "Happy Birthday" to her.

In a video captured by TikTok user @beyhivelive, Beyoncé looked both delighted and emotional at being serenaded by the music icon and jumped up and down with excitement before embracing Ross as the song ended.

"Thank you so much, you are so amazing,” Beyoncé told Ross on the stage as they held hands. “This is the legendary Diana Ross! There would be no me without you and thank you so much for all of your sacrifice and your beauty and your grace. Thank you for opening doors for me. Thank you so much.”

“You sang 'Happy Birthday' to me so I wanted to sing it to you,” Ross replied with a smile.

The sweet moment between the two singers was captured by many of the famous faces in attendance at the show, with Kim Kardashian sharing a video on her Instagram Story. “A birthday song from @dianaross,” she wrote alongside the clip.

Khloe Kardashian, Penelope Disick, Kim Kardashian, North West, Kris Jenner, Lauren Sanchez and Jeff Bezos watch Beyoncé in Los Angeles.

Kevin Mazur/WireImage for Parkwood

Kardashian, 42, and her sister Khloé Kardashian took Kim’s daughter North West, 10, to the show, along with their niece Penelope Disick, 10, who is the daughter of their sister Kourtney Kardashian.

Beyoncé serenaded Ross back in 2019 when the Motown singer was turning 75.

The Supremes singer celebrated her milestone birthday with a star-studded gathering at the Warwick in Los Angeles, before moving the celebrations to the Hollywood Palladium.

Kim Kardashian shared a clip of the moment on her Instagram Story.

Kim Kardashian/Instagram

As guests including Ross’ daughter Tracee Ellis Ross, son Evan Ross and her daughter-in-law Ashlee Simpson Ross gathered around her cake to sing "Happy Birthday," Tracee, 50, spotted Beyoncé in the crowd and asked her to lead things off.

Beyoncé has previously opened up about how Ross is one of her musical inspirations. She also played a fictional girl group singer turned solo star based on Diana in the movie adaptation of the hit musical Dreamgirls.

Kim Kardashian watched Beyoncé in Los Angeles.

Kevin Mazur/WireImage for Parkwood

“She’s an all-around entertainer: a great actor, a good singer, and a beautiful, elegant woman,” Beyoncé previously told Entertainment Weekly about Ross.