The Ugly Truth enters UK box office chart at number one
The film crept past GI Joe: The Rise of Cobra, taking nearly £2 million in ticket sales over its opening weekend.
It co-stars Gerard Butler and follows Katherine as a romantically challenged morning show producer whose search for Mr Perfect has left her hopelessly single.
Her bosses then team her with a hardcore TV personality (Butler) who promises to spill the ugly truth on what makes men and women tick.
Last week's number one film Harry Potter and the Half-Blood Prince slipped two places to this week's number three, while guinea pig action flick G-Force dropped to number four.
Former number one The Proposal fell to number five.
Katherine has recently finished filming Five Killers, an action comedy co-starring Ashton Kutcher, Tom Selleck and Catherine O'Hara.