Coach Patrick Kisnorbo has hailed Melbourne City's character after they won their first A-League title and sealed the premiership-championship double with a comeback 3-1 grand final win over a 10-man Sydney FC.

Sydney's Kosta Barbarouses opened the scoring in the 21st minute, with the brilliant Nathaniel Atkinson responding two minutes later, before Luke Brattan's 35th-minute red card turned the game in City's favour in at AAMI Park.

Captain Scott Jamieson put City ahead from the penalty spot late in the first half, while Scott Galloway slammed home a third in injury time to seal a premiership-championship double in Kisnorbo's first season as coach.

Sydney FC were seeking a record third-straight championship but City's dominant win avenged their loss in last year's grand final - and completed a stunning recovery after they started the season with four losses from their opening six games.

"It's a credit to them (the players) because they've had a fantastic attitude, a fantastic work rate," Kisnorbo told reporters.

"When things weren't looking promising at the start (of the season), there was never doubt, never questions asked - it was 'how can we keep working, and improving?' And that's what they did to put them in a position like tonight.

"I've always said about character. We went 1-0 down and straight away, (two minutes later) Nathaniel scored which was fantastic.

"So I'm happy with their character and the way they've gone about this season."

City were without Socceroos Jamie Maclaren, Curtis Good and Connor Metcalfe while Sydney missed internationals Rhyan Grant, Andrew Redmayne and Ryan McGowan.

In their absence, Atkinson proved the star of the show, with the 22-year-old claiming the Joe Marston Medal for man of the match after giving the Sydney defence headaches throughout from the right wing.

City started like a house on fire in front of a parochial sellout crowd of 14,017 at AAMI Park, which was at 50 per cent capacity.

But Sydney struck the first blow when Barbarouses cut inside and unleashed a scintillating right-footed strike from outside the box past Tom Glover.

City hit back two minutes later when Stefan Colakovski picked up the ball inside his own half, powered down the left wing and danced past the Sydney defence before squaring to Atkinson, who blasted a shot into the roof of the net in the 23rd minute.

Brattan, who was booked for a challenge on Aiden O'Neill in the 25th minute, up-ended Marco Tilio with a sliding tackle and received a second yellow card - his send-off handing his former club City the upper hand.

It was the 31-year-old's first career red card.

Eleven minutes later, City made their numbers advantage count, when Sydney's Anthony Caceres fouled Adrian Luna just inside the area - and Jamieson coolly converted.

Sydney coach Steve Corica felt Caceres hadn't fouled Luna, while he also lamented Brattan's first yellow card.

"The game was shaping up to be a very good game until - obviously in my opinion, the referee made the wrong decision in sending Brattsy off, and the penalty," Corica said.

"Two decisions that changed the whole game completely and destroyed everything."