By Channel Nine's own measurement, Today has already lost the 2017 ratings battle to Sunrise. Yet Nine refuses to raise the white flag - and Seven refuses to claim victory.

What's going on?

A look at last year's legal stoush between the two networks helps explain things.

According to Nine, a news or current affairs program wins the year as soon as it wins more than half the 40 official ratings weeks. Using this yardstick, it has already declared three programs to be "unbeatable" in 2017: A Current Affair, and Nine News in Sydney and Melbourne.

The problem for Nine is that Sunrise has just notched up 21 metropolitan weekly wins.

When Today achieved the same result last year, it crowned itself "Australia's No. 1 breakfast show". Seven swiftly sued its arch-rival, pointing out that Sunrise had a bigger audience once regional viewers were counted. Moments before they were due to face off in the Federal Court, they settled - and Nine agreed to tone down its promotions.

But not before a bitter (and very public) spat.

Mark Calvert, Today's executive producer, alleged Seven was "behaving like the narky kid who gets beaten in a kick-about on the oval... so he takes his ball home". Seven fired back, claiming Nine was suffering from - ahem - "premature elation".

Seven has long insisted that Nine's metrics are rubbish, and annual averages always trump weekly wins. Therefore, a victor cannot be determined until the end of the ratings season. If Seven changed its mind now - as tempting as this must be - it would be accused of hypocrisy.

But why hasn't Nine conceded defeat?

We have just passed week 30 of the 40-week official ratings season. (Easter and summer holidays are excluded, because many viewers are away.)

Of those 30 weeks, Sunrise has won 21. Even if Today dominates for the rest of the year, it can hope for 19 weekly victories as best.

At face value, two of Sunrise's weekly victories are draws - but only after they're rounded off. This explains why Nine isn't rolling over just yet.

Drill down into these "draws", however, and you find that Sunrise won both: by 644 viewers in one week, and just 324 viewers in the other.

This is where it's useful to examine audience averages.

So far this year, in the official ratings period, Sunrise is averaging 291,000 city viewers to Today's 283,000. Throw in regional viewers, and the gap widens: 517,000 to 429,000. Even when summer and Easter are included, Sunrise remains ahead.

Of course, these low averages reflect the fact that no one watches a breakfast show from start to finish. A Fairfax Media analysis, in March of this year, showed that 2.6 million viewers caught at least five minutes of Sunrise - hosted by David Koch and Samantha Armytage - across a working week. Meanwhile, 2.4 million tuned into Lisa Wilkinson and Karl Stefanovic on Today.

While the two commercial programs have declined slightly, ABC's News Breakfast - hosted by Virginia Trioli and Michael Rowland - has grown by several thousand to a 2017 national average of 249,000.

The resurgence of The Block, which is enjoying its best ratings in years, has helped Nine claim five weeks overall. Yet Seven leads with 25 weekly victories, averaging 29.6 per cent of prime time viewers to Nine's 28.2 per cent and Ten's 18.2 per cent.

"Even a small change in ratings can have a big effect on revenue," says one commercial network insider. "No one's taking anything for granted. We're fighting for every last viewer."