Diana Ross sings Happy Birthday to Beyoncé

Beyoncé got emotional as the Supremes singer emerged at the end of her Los Angeles show Monday night to serenade her along with the sold-out crowd. Amid Ross' grand entrance, the pair embraced before the 79-year-old prompted the crowd to help her mark Beyoncé's 42nd year.

"I'm here to celebrate Beyoncé's birthday. We want to ask you to put all of your flashlights in the air — high in the air, everybody. We want you to sing 'Happy Birthday' with me, are you ready?" Ross said, and the entire venue sang along.

When the song finished, Beyoncé hugged Ross once again, and spoke a brief tribute to the ex-Supremes performer. Ross wasn’t Bey’s only special guest Sunday night, however. Kendrick Lamar also swung by to assist in performing “America Has a Problem,” surprising fans with a rare live performance of his verse on the song’s May-released remix.

Bey also gave an emotional birthday speech during the show, thanking her fans, family and former Destiny’s Child bandmates for their impact on her life. “I’m thankful to be alive,” she told the crowd, fighting back tears. “I’m thankful to be on stage. I’m thankful to look out and see your faces. I’m thankful to be able to provide a safe space for all of y’all. I’m thankful for music, for the ability to heal myself through music which then heals all of you.”