The event kicks off with the age group competition, with super distance and super sprint races with about 100 entrants so far, including from Waikato, Kawerau and Auckland.
Miller said that would be followed by the elite racing which starts at 9am with 25 of the country's top triathletes, including three who competed at the Commonwealth Games.
The elite racers would complete the Super Sprint course twice back to back, he said.
After a 350m swim, a 7km bike ride, and 2.5m run, the athletes go back through the transition area and do it all again, Miller said.
Among those taking the start line in the elite race is Ryan Sissons, Taylor Reid and Nicole van der Kaay, and Tauranga young gun Hayden Wilde.
Emerging talent Hannah Knighton from Tauranga is also one to watch because she has been nominated for a Halberg Award, Miller said.
Sissons' German training partner Max Sehwetz was also competing.
Ironman Cameron Brown and his son Joshua would also be there, but whether Brown raced was something the athlete was keeping close to his chest, he said.
Wilde, 20, said he was rapt to be racing in the new format.
"This sort of format has exploded overseas. It's super sharp, super fast, super exciting, and it will be amazing for spectators to watch the top 10 elite in New Zealand going at it."
Wilde said it was a fiercely competitive event and anything could happen.
"It really does depend on how you feel on the day, and how fast you are through the transition area."
Wilde, named Vodafone Junior Sportsman of the Year at the Bay of Plenty Sports Awards, said he did not plan on going easy on any of the other competitors, especially the "Commonwealth Games boys" and was "super excited" to be taking them on.
"I hope to come in the top five. Anything in the top five I'd be really satisfied with that."
MIller said entries were still being accepted including on race day.
Eves Surfbreaker Triathlon:
When: December 27, from 6am-1pm
Where: Starts near Mount Maunganui Surf ClubFirst race: 7.20am, Mount Main Beach
Age Groups: Sprint U16, 16-19, 20-35, Over 35 male and female: Super Sprint 12-14, U12 and Under, Open Male and Female; Teams compete against each other.
Sprint: 750m swim (2 laps), 19km cycle (3 laps), 5km run (2 laps); Super Sprint: 375m swim, 7km cycle, 2.5km Run; Teams: Sprint and Super Sprint Distance.
Swim: Triangular course at Mount Main Beach; Cycle and run: Laps of Marine Parade.
Registrations and late entries, 6am-7am, Mount Surf Club.