The Jets huffed and puffed, but couldn't blow down a resolute Adelaide defence, as desperation won the day at McDonald Jones Stadium.
Danielle Colaprico gave United the early lead, but Newcastle struck back immediately with a tidy finish to in-form striker Katie Stengel.
Adelaide were not to be outdone, however, and nicked the advantage just before halftime through Katie Naughton. Emily Van-Egmond had a slow day at the office, and couldn't spark her side back into the contest, with United prevailing 2-1.
The unlikely win moves Adelaide equal on points with eighth-placed Western Sydney, while Newcastle remain second for the time being, with Sydney FC breathing down their neck.
Cassidy Davis was pulling no punches after the performance.
"In the first half we started poor, we can't afford to do that against a team that has anything to go for," she said.
"We were trying to go for the game and sometimes it doesn't happen. Now it's about regrouping and working for next week."
Danielle Colaprico scored the winner, and said her side had been building towards this.
"It's about time Adelaide got what we deserved, we've played great soccer and not scored goals," she said.
"It's always hard playing away from home and we stuck together as a team."