ET was on the scene at Madonna's L.A. concert Thursday night as the Material Mom gave Dodger Stadium an extra "sticky and sweet" treat: Britney Spears took the stage! But Madonna had a second huge musical surprise in store for the crowd, too!

Half way through Madonna's hit song "Human Nature," Britney made her way onto the stage for a jaw-dropping, joint performance -- where the two simultaneously sang, "We're not sorry -- It's human nature." After the duet, the pop princess made an outfit change and came back to watch the show!

If that surprise weren't enough, Madonna also shared the stage with pop sensation Justin Timberlake!

Madonna's children -- Lourdes, 12, and Rocco, 7 -- were brought out from the backstage area just ten minutes before the big performance kicked off to watch their mom rock the house. Also on hand for Madonna's big LA show were A-list star Jennifer Lopez, Heidi Klum, Kate Moss, Lucy Liu, and Hayden Panettiere!

Madonna and Britney famously took the stage together at the 2003 MTV VMAs.