PORT Adelaide and the Crows would be guaranteed just one Showdown each season under a radical new fixture concept being promoted by new AFL chief Gillon McLachlan — and the SA rivals are united on keeping their two annual derbies.

Adelaide Football Club chairman Rob Chapman last night sent a strong “hands off” message to AFL House by noting: “Showdowns have become an event, not just a footy match, in this State.”

McLachlan has proposed the 22-round home-and-away fixture be drawn for just the first 17 weeks of the season with the 18 league clubs playing each other once.

At the end of round 17, the 18 clubs would be split into three groups — teams 1-6, 7-12 and 13-18 — and drawn to play the five rivals in their group in the last five weeks of the home-and-away season.

Had this system been in place this year, there would not have been a second Showdown. At round 17, the Power would have been seeded in the 1-6 group; the Crows would have been in the 7-12 group.

McLachlan revealed the grouping system for the five double-up games was among eight proposals the AFL executive are considering — “And that’s probably a preferred scenario,” he said.

“I don’t mind it,” he added.

“You play every other team once and then you’d have three rounds of six — they’d all play each other once and they’d give you your 22 games.”

Both Chapman and Power chief executive Keith Thomas last night questioned how this concept works for the betterment of the clubs. The Crows and Power season-ticket and corporate sales at the Oval would be significantly dented if either club did not have a home Showdown in its annual draw.

“There would have to be significant benefits in other parts of the fixture, or a compelling case put forward, to change our minds,” Chapman said.

“We understand the need for the AFL to ensure there are as many meaningful games in the fixture as possible.

“But to take one of the Showdowns off the calendar would be a huge loss for both the Crows and Power, and South Australia.”

Thomas said: “Any fixture change that contemplates removing a guaranteed blockbuster such as a Showdown would need to provide a lot of upside.

“The aim of the AFL is to provide the competition — and the fans — with closer and more meaningful games across the home-and-away season. As a club, we support that idea.

“It’s hard to imagine any fixture change providing more uncertainty and excitement than the incredible scenario we have coming up this weekend for the last round of the home-and-away season.

“Perhaps the answer is to sit tight at this stage and allow the clubs to strengthen and even out naturally in the post-expansion era before we go making any radical changes.”

Beyond being rejected by AFL clubs for denying them commercially attractive games such as two Showdowns in Adelaide, two Western Derbies in Perth and two Collingwood-Carlton derbies at the MCG, McLachlan’s concept allows for tanking — teams deliberately losing to avoid sixth position at round 17.

McLachlan’s system makes it more attractive — by an easier draw — to be placed seventh rather than sixth at the end of round 17. The seventh-ranked team would play teams 8-12 for the last five weeks of the qualifying season; the sixth-placed side would get the more challenging draw of teams ranked 1-5.