Article continues below advertisementKeith Urban may be forgetting more than just lyrics these days.During his concert at the Bridgestone Arena in Nashville on Friday, October 17, the country star blanked on the words to his hit song "The Fighter" - the same tune he originally wrote for his estranged wife, Nicole Kidman, back in 2016.Article continues below advertisementSource: MEGAKeith Urban forgot the lyrics to 'The Fighter' during a Nashville concert.