Carrusca scored one goal and set up another for teammate Fabio Ferreira as Adelaide climbed to third on the A-League ladder with Friday night's home victory.
Carrusca is considering an improved contract offer from Adelaide, having rejected the club's initial bid.
The mercurial midfielder is expected to decide within a week, and his coach Josep Gombau on Thursday made a public appeal to Carrusca to stay in Adelaide.
While money looms a sticking point, he was priceless for the Reds on a rain-soaked Coopers Stadium as they took third spot from the sagging Mariners, with one win from their past six games.
Carrusca sweet left-foot broke the game open in the 33rd minute after a canny build-up featuring Ferreira and Osama Malik.
Ferreira, wedged on a sideline, shrewdly played into the path of a charging Malik, whose cut-back pass rebounded from a Mariners defender to Carrusca, who coolly scored from 10 metres.
Some 13 minutes later, Carrusca turned provider when he cruised toward goal and, when five metres out and poised to strike, instead softly laid-off sideways to Ferreira.
The winger slotted his sixth goal of the season for Adelaide, who have lost just once in their past 10 matches.
The Mariners, now fourth on the ladder but level with Adelaide and fifth-placed Melbourne Victory on 27 points, showed more scoring intent the second half.
And they went close: a Bernie Ibini blast was spectacularly saved by Adelaide 'keeper Eugene Galekovic diving high to his right, and a Matt Simon header almost shaved the far post some 10 minutes later.
But the spotlight soon returned to Carrusca.
In the 60th minute, he conjured a precocious shot - with a first-touch from the outside of his valued left boot, he lobbed over the Mariners' keeper but the ball fell on top of the net.
Carrusca managed another saved shot before being leaving the field to a standing ovation when substituted in the 79th minute.