Veteran entertainer Donny Osmond has apologised to fans after he and his sister Marie were forced to cancel their Saturday night (19Apr14) concert in Las Vegas. The sibling duo is currently performing a residency at the Flamingo Las Vegas hotel and casino, but Marie Osmond was feeling unwell, prompting the pair to pull the weekend gig. Taking to his Twitter.com page on Tuesday (22Apr14), Donny wrote, "So sorry. Marie was under the weather." After receiving messages of support from followers, he replied, "Everyone is fine now. Thanks. Back on stage tonight!"