But there was no stopping a Buller side whose forwards laid the platform for one of the fastest backlines seen in Ruatoria this season, and they stretched the score to 35-7 by halftime.
Buller skipper and halfback Andrew Stephens was given an armchair ride by his pack.
First five-eighth James Lash, who scored a try and converted seven of the eight five-pointers, was all class as he stretched the Coast defence with perfectly weighted passes and tactical kicking.
The Coast stunned the visitors with the try of the match five minutes into the second half.
Second-five Verdon Bartlett started the move with a superb break up the middle and a pass to left-winger Epeli Lotawa. He passed to fullback Kris Palmer, who jinked his way along the left touchline before passing to Lotawa, then taking a return pass and dotting down.
Lotawa and centre Sailosi Vatubua were always willing to take on the defence.
The Coast continued to take the game to Buller and came close to another try when Vatubua was tackled into touch as he tried to ground the ball, which was lost forward.
Buller launched a counter-attack that finished with left-winger Iliesa Ravudra scoring the first of his two tries.
With Lash converting one of the two tries, Buller led 47-12 with 13 minutes remaining . . . and it was time for another Coast try.
Following good work from the forwards, Vatubua was rewarded for another strong game with a five-pointer in the 78th minute.
“At least we scored the last points,” shouted a happy Coast supporter.
He spoke too soon.
With time up, replacement flanker Kahu Parata bagged a try, which Lash converted.
“We always knew Buller would be tough,” Coast co-coach Troy Para said.
“They’ve been up around the top four for the past few years. We had patches of good play but we didn’t help ourselves with lapses of concentration, which gets punished when you play teams as good as Buller.
“But take nothing away from them, they deserved to win.”
East Coast 17 (Neihana Ratahi-Brown, Kris Palmer, Sailosi Vatubua tries; Palmer con).
Buller 54 (Andrew Stephens 2, Michael Lealava’a 2, Iliesa Ravudra 2, James Lash, Kahu Parata; Lash 7 con).
HT: 35-7.