Martinborough were expected to have a battle royal with Gladstone but with a vocal home crowd urging them on, Martinborough ran in four tries and triumphed 30-11.
The news was not all bad for Gladstone though as the defending Tui Cup champions lived to fight another day, having accumulated enough competition points beforehand to still make the semis.
East Coast and Bush Sports turned on the fireworks at Whareama, scoring 12 tries between them in a match won by East Coast 54-26.
Wairarapa-Bush utility back Nick Olson scored a hat-trick of tries for East Coast and added four conversions and a penalty for good measure, giving him a personal tally of 26 points.
Eketahuna needed the maximum five points to have any chance of making the semis when they played Carterton at Carterton and while they scored two tries to Carterton's one, it was Carterton who took the honours 16-12, thanks mainly to the three penalties and one conversion landed by Danny Brown.
Preliminary round standings: Greytown 22, Martinborough 21, East Coast 20, Gladstone 15, Pioneer 13, Eketahuna 11, Carterton 10, Bush Sports 5.