Channel Seven is suing the Nine Network over claims Nine's morning program The Today Show has higher ratings than Seven's competing program, Sunrise.
A statement of claim was filed in the Federal Court on Wednesday afternoon and a hearing is scheduled for Friday.
Is Karl Stefanovic the reason why Nine's Today show has beaten Seven's Sunrise in the TV ratings every month this year?
The stoush centres on Nine's claim, in a press release on October 22, that Today had "triumphed in the 2016 ratings year to regain the crown as Australia's favourite breakfast program".
Nine said it had won 21 of 40 ratings weeks in the "5 City Metro" metric - measuring audiences in Sydney, Melbourne, Brisbane, Adelaide and Perth.
Today had an average audience of 317,000 viewers each morning, Nine said, while Sunrise had an average of 310,000.
It is understood Channel Seven believes the ratings of Sunrise are higher than Today when regional audiences are factored in, and the network will attempt to have promotions by Nine pulled from the air that say Today has the highest ratings.
In a filing to the Federal Court, Nine's assertions are alleged to be false, misleading or deceptive.
A spokesman for the Nine Network told Fairfax Media the network was bemused by the court action, which he compared to the behaviour of Donald Trump.
"Seven's response can be equated to Donald Trump saying he will only accept the election result if he wins," the spokesman said.
In a press release in November last year, Seven also used the "5 City Metro" metric to say it had won 29.3 per cent of the overall audience share in Australia.
It is understood Seven does not take issue with the metric itself, but believes it should be used in conjunction with regional figures for morning television.
A Channel Seven spokesman declined to comment.
