The Grammy-winning singer was all smiles on Wednesday night as she joined her friend and singer Ashley Monroe in singing, "Heart Like Mine," which she co-wrote with Monroe.
The show was a preview of Monroe's forthcoming album, "The Blade," and country artists including Vince Gill and Phillip Sweet of Little Big Town also populated the small club.
Lambert, 31, and Shelton, 39, announced their divorce Monday after four years of marriage. Lambert spent most of the evening singing along from the crowd, until Monroe invited her up to participate in her encore performance.
Lambert and Shelton are among country's most popular singers. Both pick up scores of awards annually.