The musician, whose songs "Arthur's Theme (Best That You Can Do)" and "Sailing" topped the Billboard Hot 100, urged his fans to take the growing global pandemic seriously. Singer-songwriter Christopher Cross has been diagnosed with the coronavirus. The five-time Grammy winner shared the news in a lengthy Facebook post Friday. "I'm sorry to report that I am among the growing number of Americans who tested positive for the COVID-19 virus," he wrote. "Although I am fortunate enough to be cared for at home, this is possibly the worst illness I've ever had." The musician, whose songs "Arthur's Theme (Best That...