Chasing stories on David Beckham put a strain on the relationship between Rebekah Brooks and Andy Coulson, the Old Bailey has heard.
Brooks used her friendship with Victoria Beckham and her footballer husband to demonstrate the "Chinese Wall" between them as they edited sister papers, the Sun and the News of the World.
Brooks began editing the Sun in 2003 while co-defendant Coulson took over from her at the NotW, the Old Bailey heard.
Giving evidence for a fourth day, Brooks, 45, told how she had lunch with Mrs Beckham as the stories about her husband's alleged affair were afoot.
She told the Old Bailey trial: "The two papers were rivals and pretty strong rivals. I think Andy and I had been very good at keeping the Chinese Wall.
"It was a hostage to fortune discussing what we were working on. He was on the weekly, I was on the daily with more opportunity to publish.
"Beckham is a good example. So Andy would have known that I knew the Beckhams a little socially, we are not close friends but would see them occasionally for dinner. I was also trying to get Victoria or David to do things for the paper.
"He would know I had direct access to them so if he is working on a story and there is something afoot as the paper was working on the fact David Beckham was allegedly having an affair with a woman, to even mention that to me could be fatal to his paper.
"He would not know the day he mentioned it I had lunch with Victoria.
"So he may say on Thursday 'we will have the Beckham story this weekend' and I may respond 'sorry we are doing it tomorrow'. It was too complicated. Things were difficult, it was strained for a while."
Brooks, of Churchill, Oxfordshire, denies conspiring to hack phones, conspiring to commit misconduct in public office and conspiring to cover up evidence to pervert the course of justice. All seven defendants deny the charges against them.