While O'Dea and Watson took the first set 21-15, the younger O'Dea combination was having none of this and won the second set 21-14.
Read more: Beach volleyball: Japanese put on world class show
However, Sam and his partner Watson pulled rank and took the final set and game 15-11.
Harbour talents Jesse Hawkins and Alani Nicklin in first pool play took on Thomas Reid (Tauranga) and Liam Munday (Harbour).
They won first set 21-13 and then survived a scare in the second winning a marathon 32-30.
Final pool play for Hawkins and Nicklin was against Thomas Hartles (Harbour) and Paora Morunga (Tauranga) which they won but they lost 21-15, 18-21, 13-15 in a heartbreaking semifinal to Tame Malcolm and Griffin Muller.
This then meant the second time Malcolm and Muller met O'Dea and Watson in a final and the result went to seedings with O'Dea and Watson winning comfortably 21-12, 21-14.
The women's side of the draw was tighter than usual with the inclusion of more international teams from Vanuatu, Canada, Czech Republic and a second Japanese team.
New Zealand's top pairing of Julia Tilley and Shaunna Polley were the only Kiwi team to make the semis. They took on Japan's Ishii and Murakami in the first semi of the day.
Polley injured herself and took a medical time out after going down 12-21 in the first set.
The Kiwi pair dominated 21-16 in the second but were unable to come away with the win going down 16-18 in the third to the eventual winners who won over the other Japanese team of Hasegawa and Kusano 21-17, 21-16.
The Pro Tour heads to Mount Maunganui this weekend.
It will be combined with New Zealand Secondary Schools Beach Champs, with 100 plus teams entered.
The defending champions from 2015 are: Senior girls - Burnside High School, senior boys - Tauranga Boys' College, junior girls - Nelson College for Girls and junior boys - Tauranga Boys' College.