"If We're Not Back in Love by Monday" is a song written by Sonny Throckmorton and Glenn Martin, and first recorded by American country music artist Merle Haggard. It was released in March 1977 as the first single from the album Ramblin' Fever. The song reached number 2 on the Billboard Hot Country Singles & Tracks chart.
Later in 1977, Millie Jackson recorded a cover version for her album Feelin' Bitchy, which was released as a single and hit the Billboard R&B charts, peaking at #5.
In 1978, the song was released by Sonny Throckmorton on his debut album, Last Cheater's Waltz.