In the UK, "Knocked Out" was released three times. It was Abdul's first single and charted on September 24, 1988, peaking at a lowly #98. Following the success of "Straight Up" and its follow-up, "Forever Your Girl", "Knocked Out" was reissued and peaked at #41 on 19 August 1989. Finally, after the huge success of "Opposites Attract" in 1990, the single was extensively reworked by Shep Pettibone and it entered the UK Top 30, peaking at #21 on July 28, 1990.