Jay Z -- Sings Beyonce with Emotion ... I'll Always Be Her + 1 (VIDEO)

Jay Z got lost in the moment, emotionally belting out lyrics to one of his wife's mega-songs.

Jay was standing with Nick Jonas, watching Beyonce perform "1 + 1" Saturday at the Budweiser Made in America Concert in Philly.

He wasn't the only 1 caught up in the moment. Beyonce's mom Tina Knowles and Kelly Rowland joined in as well.

Who knew Jay and Nick were buds.