West Australian Elizabeth Pluimers has defeated Noosa Head’s Jordan Mercer by just four seconds to win the fourth round of the Australian Ironwoman series in Perth.

Northcliffe’s Pluimers, who started the 11.4km marathon race in second place in the summer standings, gained the series lead after former frontrunner Kristyl Smith finished a disappointing 11th place.

She is on 79 points, four ahead of Smith and seven points clear of defending champion Courtney Hancock, who claimed third place on Sunday.

Pluimers was forced to chase Mercer for most of the race after the daughter of ironman legend Darren Mercer broke away on the 1.8km board leg.

Mercer then extended her lead to almost a minute during the 3.6km run leg, before Pluimers reduced the deficit to 15 seconds in the 1km swim and passing the Queenslander on the 5km ski leg.

“I’m glad there was a bit of wind out there,” Pluimers said of the SE wind at their backs from Cottesloe Beach to Scarborough Beach.

“Jordy is an amazing athlete and made me work so hard.”

For Mercer, the result confirmed her status as a rising star in the sport.

“Mentally, to know I can do this and that I’m capable of it. It’s given me a bit of mindset to do it again.”