SYDNEY: The actress wife of Australian tennis star Lleyton Hewitt took a gossip magazine to court hoping to uncover the source of a "grubby" story which implied she was having an affair.

New Idea magazine has twice published apologies over the April article, titled "Bec's Other Man", which pictured Bec Hewitt with what they described as a "hunky American fitness trainer" named Minder Mark.

The man in the picture was in fact her brother, Shaun Cartwright, who frequently accompanies the family on the tennis circuit.

Hewitt's lawyer Andrew Harris told the South Australian Supreme Court it was a "particularly grubby" article and the former soap star was determined to discover its source so she could nail "the liar as well as the lie".

"There is no Minder Mark, his persona is a fabrication," Harris said, according to the national AAP newswire.

The magazine's publisher, Pacific Magazines, argued it could not be forced to reveal where the information came from because "newspaper rules" applied, meaning its journalists had an obligation to protect their sources.

Tom Blackburn, acting for Pacific, said Hewitt's high profile meant her affairs were in the "stream of public discourse" and attracted the "newspaper rules" governing journalistic ethics.

"She can't now say her activities and family are not matters of public interest," Blackburn said.

Glynn Hewitt, Lleyton's father, said his daughter-in-law hadn't deserved such publicity, and denied the couple put themselves forward for public scrutiny.

The court will publish its decision at a later date.