A fast-maturing Swans line-up refused to be blown away by the three-time premiership side at Unley Oval, with just one goal separating the teams at the final break on Sunday.
Sydney skipper Chloe Molloy slotted her second goal of the game to make it two points the difference, but the Crows held on for a 6.5 (41) to 6.3 (39) win.
Marinoff became the first AFLW player to reach the 100-game milestone alongside Brisbane star Ally Anderson, who played in the Lions' simultaneous fixture against Richmond.
The game was also Adelaide's 100th game as an AFLW club, meaning co-captain Marinoff has remarkably never missed a game since the inaugural 2017 season.
It was Adelaide's star Irishwoman Niamh Kelly who stole the show with her blistering pace, finishing with one goal and 29 disposals, with 706 metres gained.
But Marinoff was just as busy with 23 touches, seven clearances, 15 contested possessions and 14 tackles.
Adelaide sit fourth after a 2-3 start to the season and condemn finals hopefuls Sydney to three straight losses.
Laura Gardiner (34 disposals, eight clearances, 16 contested possessions) was exceptional for the Swans, as fellow midfielder Montana Ham had several game-opening moments.
The Swans are sixth on percentage after going undefeated in the opening four rounds.
Adelaide burst from the blocks to kick the first two goals on Sunday, but Sydney adjusted to the pace to level the scores 2.1 (13) at quarter-time.Â
The Swans continued to lift and Cynthia Hamilton and Molloy both got on the scoreboard to build a five-point lead at halftime.
The scoreboard was all square at 5.3 (33) in the third quarter, before Anne Hatchard slotted an after-the-siren goal.
Hatchard had earned a free kick within range of goal after Alice Mitchell had pushed milestone woman Marinoff in the back.
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