"All games are tough,'' Waitakere coach Paul Marshall said. "But I'd rather be going to New Caledonia than Tahiti where [Auckland] are going. And the pitch in Tahiti is poor, whereas we're going to a pitch that's not too bad at all.''
This is the first season the O-League - which determines Oceania's representative at the lucrative Club World Cup - has featured a semifinal stage, which would make Auckland's potential early exit even more surprising.
Having been beaten by Dragon on Wednesday, Auckland really needed to emerge with victory from the 41st Super City derby. But a flat performance on a rainy afternoon saw Waitakere's defence cope quite easily, ensuring Butler's 26th-minute strike proved decisive.
"Any win at Kiwitea St is a good win,'' Marshall said. "We've kept them scoreless and ... they don't go through too many games where they don't score goals. They're certainly struggling to break us down when we perform to our best.''
Auckland found that too difficult a task today and Waitakere were good value for the three points, though they also failed to create many clear-cut chances.
The first half was completely bereft of goalmouth action until Butler ran onto a clever flick from Roy Krishna and calmly slotted the ball just inside the right-hand post. Krishna then nearly made it two with an angled drive, while Auckland's attack were unable to penetrate the visitors' solid rearguard.
With their normal possession-based game getting them nowhere, Auckland played much more directly in the second spell, though Tribulietx said that was not a deliberate tactic.
"We probably should've been a little more patient on the ball, though it's difficult in the last 25 minutes when you're chasing and you want to bring the ball forward as quickly as possible.''
But route one was no more productive for the hosts, leaving Waitakere goalkeeper Danny Robinson relatively unoccupied in the closing stages.
Auckland City 0
Waitakere United 1 (Butler 26)
