AOC board member Andrew Plympton, a former St Kilda Football Club president who already had declared himself as a candidate for AOC vice-president to Roche, has called the meeting. Two other board members, believed to be Nicole Livingstone and Danielle Woodward, have joined him, making the three necessary to force the extraordinary summit. The AOC has confirmed it.

The agenda is not public, but it is certain to cover a range of issues that have had a wide airing during an increasingly testy election prologue, including allegations of bullying within the AOC, discrimination and financial profligacy. Australian sport has been on a war footing since an infamous moment at an athletics meeting in Melbourne in February, where Coates brushed aside Australian Sports Commission chairman John Wylie, saying: "I don't shake hands with liars. I don't shake hands with c...s."

The temperature rose another notch on Monday when former Federal sports minister and Coates ally Graham Richardson wrote in a column for The Australian that Coates had been the subject of a "vicious, old-fashioned" Melbourne-based smear campaign driven by Wylie and augmented by Victorian media. "There have been articles bobbing up in every Fairfax and News Corp paper, particularly in Melbourne," Richardson wrote. "This is far from a coincidence. Most of these reports emanate from a bevy of Melbourne journalists."

One of the remarkable features of this barney is the way it has opened up ancient Australian fault lines: Sydney versus Melbourne, Liberal versus Labor, even AFL versus NRL.

Some of the ill will can be traced back to 1990, the year Coates became AOC president, when Melbourne was bidding for the 1996 Olympic Games. Many Melbourne movers and shakers felt at the time, and still do, that the AOC gave the bid only lukewarm support.

Those old sectarian suspicions will not have been allayed by developments this week. On ABC radio on Sunday, Roche - who is on the St Kilda board - held up the AFL as a model organisation, especially in its "transparent" governance and its player welfare. "The AFL is streets ahead," she said. "We could learn a lot from the AFL on that front. It is an enormously professional organisation.

"We're not collaborating in Australian sport right now. It's dysfunctional in the peak bodies. That dysfunction needs to change."

Then on Monday, Melbourne Lord Mayor and former Victorian Liberal Party leader Robert Doyle tweeted: "Campaign for @danniroche1 to replace AOC 26 year incumbent John Coates seems to be gathering media/business momentum. I'm with Danni."

Coates' preferred successor - 'though not immediately - is new board member and Athletics Australia president Mark Arbib, who like Richardson is a former Federal sports minister from the NSW Labor right faction.

The board was not due to meet until May 5, the day before the election. But it is now impossibly divided, leading to calling the crisis meeting immediately.

Coates remains the pivotal figure. Even those who do not warm to his dictatorial style respect his achievements. Supporters fear that toppling him will rob Australia of its considerable influence on the International Olympic Committee, of which Coates is vice-president. Richardson emphasised this, effectively calling Roche lightweight. "To beat someone like Coates, you need more than once having been a hockey player," he wrote.

A mooted plan for Coates to assume the position of honorary president of the AOC and therefore his IOC appointment should he lose the vote to Roche is not considered viable, not least because the bad blood would not be so easily mopped up. In any case, it is uncertain that the constitution of the IOC would allow it.

Watchers say the race is tight, but secretive. A large swag of the 94 votes rest with minor sports, among whom Coates holds great sway, but whose positions are inscrutable. "But it feels like the squeeze is on," one Olympic veteran said on Monday.