Francis, 69, was scheduled to perform with Sedaka at The Capital One Bank Theatre in Westbury Wednesday night, but instead was admitted to Long Island Jewish Medical Center's coronary care unit with dangerously high blood pressure, Newsday reported.
"She really wanted to do the show and she didn't want to disappoint her fans or her dear friend Neil Sedaka," her agent Mike Church told the newspaper. "But her doctor told her that it would be dangerous. ... We expect her to be back on her feet and out doing shows very soon."
Francis is best known for her hits "Where the Boys Are," "Who's Sorry Now?" and "Lipstick on Your Collar."