Country fans who attended Chris Stapleton's concert in Buffalo, N.Y. on Sunday (July 16) got a very special surprise when Miranda Lambert casually strolled onto the stage to join him for a duet.

Lambert stopped by the All-American Road Show Tour to share the stage with the headliner and his wife, Morgane, for a striking performance of "Fire Away." It comes as no surprise that the "Tin Man" singer was there — boyfriend Anderson East serves as opener on Stapleton's tour and was celebrating a big birthday.

Watch Miranda Lambert Serenade Anderson East With "Happy Birthday"

In a video shared by the Boot, Lambert is met with screams as she takes the stage to join Stapleton for "Fire Away." While he remains on lead, Lambert and Morgane assist on harmonies after embracing in a big hug. Toward the end of the song, Stapleton turns the spotlight over to Lambert, letting her take the lead.

Lambert watched much of the show from the sound booth before taking the stage to surprise East during his earlier set, singing a slowed, darker version of "Happy Birthday" with help from the audience. East turned 30 on Monday (July 17).

This is far from the first time that Lambert, East and Stapleton have shared the stage together. In April 2016 they all sang “My Girl” in Los Angeles. Lambert has also surprised East onstage to sing Mariah Carey’s “You’ll Always Be My Baby."

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