His hits quickly became more successful, including "Hey Little Girl", "Um, Um, Um, Um, Um, Um" (his biggest hit, reaching #5 in the US pop chart and #40 in the UK, where it was his only chart success. It was also one of the top 100 on the Billboard chart in 1964), "The Matador" (the only one not written by Mayfield), "Rhythm", "Sometimes I Wonder", "Come See", and "Ain't It A Shame".