Radical format twist to test Ironman's title hold

Defending champion Ali Day laughs that the radical shake-up of the Iron Series finals feels like an attempt to knock him off the perch.

But the surf lifesaving veteran is backing himself to win anyway this weekend on the Gold Coast.

The two-day, eight-race knockout will boil down to a winner-takes-all, eight-person swim, board and ski race for the men's and women's crowns.

Five-time Iron Series champion Day has been a dominant force since claiming his first title a decade ago.

But the 10-time Coolangatta Gold winner, 34, has no room for error against a chasing pack headed by New Zealand's Joe Collins, who won both races in Newcastle's last round.

Only 16 male and female competitors remain from the 30 that lined up in round two, with four more dropping out after Saturday's fifth event, that will feature a handicapped start based on results in the first four races.

Sunday's three-race program will whittle the field down from 12, to 10 and then to eight before the first across the line at North Burleigh wins it all.

"I hope not, but it does sound like that though," Day laughed at the tongue-in-cheek suggestion the format had been tweaked to threaten his dominance.

"It's a different format, but it's exciting and you can't change it so I'm just going to be challenged by it and I'm looking forward to it.

"At the end of the day it's eight guys in that final and you've still got to go and win it ... deliver in the biggest moments.

"In my career I've been able to do that.

"There's a lot of racing to get through Saturday just to make it to Sunday's final.

"I'm still a big believer if you do the little things right you'll be rewarded."

Collins, 22 and now based on the Gold Coast, would be the first New Zealander to win the title.

Defending women's champion Lana Rogers is aiming to join Kristy Cameron as the only four-time series winners since females began racing in 1990.