Auckland have snapped out of their mid-season form slump, returning to the top of the A-League Men table with a 1-0 win that exposed Sydney FC's Achilles heel.
A solitary goal from striker Sam Cosgrove - his seventh of the campaign - helped Steve Corica's men end a run of three-straight games without a win at GoMedia Stadium on Saturday.
Auckland climbed above Newcastle into first spot with the victory but could drop to second if the Jets continue their red-hot form away to Adelaide on Sunday.
Third-placed Sydney remain one win off top but were unable to recapture the intensity of last week's derby victory over Western Sydney.
"I don't think we created enough chances to get something from the game," Sydney coach Ufuk Talay said.
Throw-ins were particularly troublesome for the Sky Blues with Cosgrove putting Auckland ahead after 20 minutes when Sydney failed to adequately clear a long throw into the box.
Francis De Vries sent the half clearance back into the mixer for Hiroki Sakai to head across the six-yard box where Cosgrove was on hand to poke home.
"I'm disappointed with the way we conceded," Talay said.
"A long throw, a second phase and we switch off and don't stay with the player and allow a simple tap-in to happen."
Twice more in the first half, Sydney breathed a sigh of relief off throw-ins.
Off one delivery Harrison Devenish-Meares tipped a goal-bound Louis Verstraete header over the bar.
The goalkeeper then allowed Cosgrove a golden chance to double Auckland's lead a few minutes later when he rushed off his line but misjudged the ball's flight.
The ball trickled to Cosgrove who looked certain to score before a vital intervention from Paul Okon-Engstler blocked his shot.
The Sky Blues survived until halftime when Talay threw Joe Lolley into the action at the expense of 16-year-old Akol Akon.
Lolley's introduction immediately gave Sydney a spark with Tiago Quintal rattling the post.
Guillermo May hit the woodwork and Cosgrove was denied by a brilliant Devenish-Meares save as Auckland pushed for, but couldn't land, a second goal.
Corica remains undefeated in Auckland's four games against his former club in the ALM and the Australia Cup.
"Overall it was a really complete performance," said Corica, who lavished praise on goalkeeper Michael Woud after an error-strewn run in January.
"I think Michael stood up, his mentality was strong and very positive and he made some very important saves for us."
Auckland playmaker Lachie Brook failed to finish Saturday's match with back spasms.
