Triathlete Clayton Fettell rebounded from a disappointing performance at the national championships to successfully defend his Port Macquarie 70.3 title.

Fettell led a solid professional field out of the 1.9km swim and then smashed his rivals in the 90km cycle, giving him a decisive buffer for the 21.1km run.

He won Sunday's race in three hours 50 minutes 15 seconds, well clear of Tim Berkel's 4:54:45, while New Zealander James Bowstead was third in 3:57:08.

Fellow Kiwi Britta Martin won the women's race.

Berkel won the national 70.3 (half ironman) title a week ago in Mandurah, WA and Fettell was sixth.

"Last week at Mandurah I got smoked, but I couldn't be happier with Berkel taking that win," Fettell said.

"I was in the gutter on Monday after the race, so I rang my coach (Grant Giles) and he was the one who got me through the solid week which was very hard mentally.

"To come out of that for a win today, I'm very happy.

"I love racing in Port Macquarie and stoked to go two years in a row."

In the women's race, Kat Baker dominated the swim and bike and appeared to have the race in the bag when she led by 11 minutes 30 seconds at the start of the run.

But Martin scorched the run to win in 4:32:26, while Rebecca Hoschke was second in 4:37:07 and Baker fading to third with her time of 4:39:41.