SYDNEY, AUSTRALIA - NOVEMBER 21: Sydney FC celebrate after winning the FFA Cup Final match between Sydney FC and Adelaide United at Allianz Stadium on November 21, 2017 in Sydney, Australia. (Photo by Zak Kaczmarek/Getty Images)

Sydney FC claimed their first FFA Cup with a hard-fought 2-1 victory over Adelaide after a pulsating night at Allianz Stadium.

The Sky Blues capped off a brilliant 2017 completing a calendar treble, winning the A-League Championship, Premier’s Plate and the FFA Cup.

They have only lost two competitive games this year.

But last night they didn’t have it all their own way.

If Adelaide, who were gunning for their second FFA Cup, were feeling intimidated by the home crowd, they weren’t showing it.

Andrew Redmayne produced a fine reflex stop to deny Ryan Kitto after 11 minutes.

The Reds had the best of the early play, but it was Milos Ninkovic who opened the scoring, putting Sydney ahead in the 19th minute after a fine build up from Alex Brosque and Bobo.

They had a chance to double their lead 15 minutes later, but Bobo fired his shot straight into Paul Izzo.

Just after the restart, Adelaide had a chance to level with a free kick just outside the area.

It was a brilliant effort by Ben Garuccio who took the kick which left Redmayne comfortably bamboozled, but it was the crossbar which denied Adelaide this time.

Karim Matmour pounced on the rebound but could not direct his header.

The Reds kept pushing but would have to wait until the 67th minute before their efforts were finally rewarded.

Ersan Gulum sent a long ball from the left to the unmarked Nikola Muleusnic.

Mileusnic turned Michael Zullo inside out before slotting a crisp shot into the top left corner.

As the clock ticked towards 90 minutes, Sydney were denied twice by Izzo, meaning the game would head into extra time.

Adelaide had several golden chances in the first period of extra time but could not finish.

And after 111 minutes of ferocious football, Sydney made them pay.

Adrian Mierzejewski sent a perfectly weighted free kick deep into the box which left Adelaide defenders with just enough uncertainty to allow Bobo to jump unchallenged, his header nestling into the bottom corner of Izzo’s net.

But the biggest talking point of the night came late in the second period of extra time.

Chasing a late equaliser, veteran defender Michael Marrone wanted to take a quick throw in but the ball kid refused to hand over the ball.

Marrone tackled the ball kid as he attempted to wrestle the ball free from his arms, and in the process sparked a melee between almost all players and coaches. Marrone was given his marching orders for his brain fade.

A tense final few minutes followed as referee Kris Griffiths-Jones added five minutes of stoppage time to account for the scuffle, but with Adelaide now a man down, the Sky Blues held firm to secure the win.

In the trophy presentation, Sydney invited the ball kid at the centre of the controversy to join their celebrations.

Michael Zullo gave his medal and Matt Simon lifted the trophy with the boy.

Former Socceroo goalkeeper Mark Bosnich said there was no place for such an incident but added there was also no place for the ball kid’s actions.

“You should never ever do something like that to a ball boy,” he said.

“But one must say the ball boy did turn away from Marrone rather than just throwing him the ball.

“The lesson is throw the ball back to him. That’s it.”

After the game Sydney coach Graham Arnold praised his team but was also congratulatory of their opponents.

“I thought it was a fantastic game of football. Adelaide played well but overall it was an outstanding effort by us with only a 3 day turnaround from the last game.”

“It’s about showing them that we are strong. We saw them on the ground and it gave us a bit of energy.”

“They are a fantastic group of players and they are hungry to win. We are having a good time. But for me that is the first of three trophies but a third in this calendar year.”

“I told the boys yesterday there will be no celebration. We go inside and recover quickly for our next game against Brisbane. We will find a date we can celebrate but for now it is about being professional.”

Adelaide coach Marco Kurz said he and Marrone apologised to the boy after the game.

“I said after the game to the ball boy, ‘I am sorry in this moment’ and also to the dad,” he said.

“I will say it’s not the character for Mickey (Marrone).

“You know Mickey he is very down in the dressing room and I think he spoke with the boy.

“It’s not his nature and now I hope after the talked it (the boy) was OK.

“From my side and also from the players’ side we say sorry.

“He is one of the most quietest persons I know in the sport.”

Mierzejewski was awarded the Mark Viduka medal for best on ground.

The midweek final means both teams now have a short turnaround before their next A-League fixtures.

Sydney will welcome Brisbane to Allianz Stadium on Saturday night while the Reds have an extra days rest, taking on the Wanderers in Adelaide on Sunday evening.