Friday night (April 1) the Academy of Country Music kicked off the fourth annual ACM Party for a Cause festival at the Las Vegas Festival Grounds, as Carrie Underwood headlined the special ACM Women of Country night with a very special surprise guest.

There was an amazing all-girl lineup to get the stage ready for Underwood, including Cam, Kelsea Ballerini, Martina McBride, Kellie Pickler, Maddie & TaeLauren Alaina, Kelleigh Bannen, Brandy Clark and Jana Kramer.

But Underwood's support went beyond that. Miranda Lambert made a surprise appearance to a shocked crowd to help Underwood out on their duet, "Something Bad." Watch the video above to see the girl power in action as the two friends completely own the stage.

That wasn't the only time Underwood shared the stage on Friday night. Alaina, Bannen, Kramer and Pickler made their way back to the stage to join the blonde powerhouse on her hit, "Before He Cheats."

The crowd gave so much love to the "Heartbeat" singer that Underwood came back for two encore songs, including “Smoke Break” and “Something in the Water.”

The night also featured special ACM Award presentations, including Ballerini's New Female Artist of the Year trophy, which she received in front of the entire crowd. Underwood was also presented with the ACM Lifting Lives Gary Haber Award for her work with providing musical instruments to various public schools around the country. 

The ACM Party for a Cause will wrap up Sunday night (April 3) after the 2016 ACM Awards, when Kenny Chesney takes the stage to play a full set following his awards show performance.

The ACM Awards will air live from Las Vegas Sunday night at 8PM ET on CBS.

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Watch Carrie Sing Dolly Parton: