After the sacking of coach Phil Moss on Friday, interim boss Tony Walmsley urged a reaction from the players and that's what he got at Central Coast Stadium on Sunday.
Ferreira's 74th minute strike and a standout performance from shot-stopper Liam Reddy, who has made more saves than any other goalkeeper this season, ensured the Mariners posted just their fourth win in 20 outings.
The victory however, still leaves them in eighth spot and five points away from sixth-placed City.
After the disappointment of being denied game-time by Moss last week, skipper John Hutchinson lead the side out Sunday to match the league record with his 221st appearance.
Both sides came out on the attack in what was a frenetic start to the match.
With the Mariners giving Robert Koren way too much space and time on the ball, the Slovenian put Reddy to work inside two minutes while Aaron Mooy also drew a save from the 'keeper just moments later.
Nick Fitzgerald fired back for the Mariners but was denied by City gloveman Tando Velaphi as Isaka Cernak blazed the post in an action-packed opening 10 minutes.
City began to take hold midway through the first half and looked like breaking the deadlock twice more.
Safuwan Baharudin set up David Williams with a superb ball, with Josh Rose making the crucial block to deny the goal-bound striker.
Mooy then played a perfect corner into the box with Reddy doing well to clear Josh Kennedy's ensuing header.
Former Socceroos striker Kennedy fired a couple more shots, first with his foot and then with his head, Reddy stopping both efforts.
The Mariners emerged from the break desperate to take the lead with Portuguese import Ferreira launching on a great ball from Nick Montgomery but sent it just over.
Ferreira threatened again in the 56th minute this time setting up Fitzgerald with a pinpoint cross, the striker unable to burry the header.
Conner Chapman brought down Cernak just outside the box and would be made to pay with Ferreira giving the Mariners the 1-0 lead from the free-kick.
Cernak took the first touch off the set-piece to set up Ferreira who drove the ball low and right for his fourth goal of the season.
Reddy ensured his team got the three points, making a point-blank save to deny Iain Ramsey in the final minute.
Walmsley praised his charges for being able to put the events of the week behind them.
"A good man lost his job and if you've got an ounce of compassion you'll feel for him," he said.
"But professional sport is a ruthless business and you have to dust yourself down pretty quickly and do what's required and that's what they've done."
Walmsley, who will remain in charge until the remainder of the season, says the finals are not out of reach.
But it will be no easy task for the Mariners, who face a tough run home playing title favourite Melbourne Victory away twice, second-placed Wellington Phoenix away and host leader Perth Glory in their last eight games.
First however, they travel to Adelaide who has slipped to fifth after back-to-back defeats.
"You'd like to think we could made the finals. I'm an eternal optimist," he said.
"Why not? Adelaide are in a bit of a slump. I don't want to fuel their fire but we're going to go down there to try to win the game."
Yet again City came undone in Gosford, where it has never tasted victory.
City coach John van't Schip knows the loss could be costly as the battle for play-off spots heats up.
"We knew we had to win if we wanted to consolidate sixth spot," he said.
"It's a fact we have problems when we come here.
"I can't tell you why. You have those opponents and the Central Coast for us is a difficult one."
