The win is just Adelaide's second of the season and is also just the Mariners' second loss of the year and comes as a massively surprising result based on the recent performances of both clubs.
The Mariners actually started well and really should have opened the scoring in the early stages but poor finishing prevented them from finding the goal that they needed.
In the seventh minute the Mariners had two golden opportunities but couldn't put either away as Trent Saisbury's miscued effort fell to Daniel McBreen, who somehow missed a simple chance, letting the Reds off the hook.
That lead to a period of dominance from Adelaide, and they went close twice with Diogo Ferreira finding the side netting in the 18th minute, before they found the goal in the 25th minute.
That goal came through Bruce Djite who was found by a Sirgio Cirio cross after an impressive run and put away the effort to give the hosts the lead.
The Mariners seemed stunned and their frustrations began to show with yellow cards being shown for dissent, but they did little to stop Adelaide getting more chances.
In the 40th minute a goalkeeping error saw Adelaide double their lead and again Cirio was the provider as he sent the ball in for Ferreira who was able to nutmeg Liam Reddy to make it 2-0 at the break.
An odd goal made it 3-0 in the 54th minute as Reddy and Cirio were looking to get the ball only for Reddy to stop thinking the ball had gone out, with no whistle Cirio gained possession and easily passed the ball in to the back of the empty net.
The Mariners looked to go for it, having enough possession to have an impact but not able to break through an Adelaide United defense that seemed renewed by the goal scoring up the other end.
Things were made even worse as time ran out with a fast counter attack saw Jeronimo run in and hit a powerful strike past Reddy for the final score line of 4-0.