A 90th-minute own goal saw Melbourne Victory's nine-game undefeated run against Adelaide United come to an end with a 1-0 loss at AAMI Park on Friday.
Bruce Kamau's last-gasp effort was diverted in by Scott Galloway, ending Adelaide's winless streak in all competitions against defending champions Victory that stretched back to 2011.
It looked like the visitors' impressive record would resume as they came close to an opener seven minutes before the break, Gui Finkler rattling the crossbar with a 30-yard free-kick that had Eugene Galekovic beaten.
Victory failed to build upon that opportunity in a drab second half that included few chances, and, in a bid to change the outcome of the game, Adelaide coach Guillermo Amor sent Kamau on with 16 minutes remaining.
The 20-year-old - making just his 20th A-League appearance - was picked out at the back post by Stefan Mauk and beat Danny Vukovic at his near post following a ricochet off Galloway.
Adelaide jump to within two points of leaders Brisbane Roar and extended their unbeaten run to 12 games, while Victory are in danger of slipping out of the play-off-places.