If there ever was a sign Sydney FC cannot take the A-League title for granted, it was their 2-1 undoing by a Newcastle side playing almost 80 minutes with 10 men.

The script to Saturday's one-versus-two Grand Final rehearsal was veritably mad, and memories of the Sky Blues' second loss this season will be remembered for one protagonist. Jordy Buijs, the Sky Blues' defender responsible for Roy O'Donovan's 14th-minute dismissal -- by way of copping a punch to the face -- conceded the penalty for the Jets' opening goal.

Buijs then delivered the free-kick for Bobo's equaliser, before Andrew Nabbout's latest screamer handed Newcastle their first win over Sydney in 16 meetings and cut the Sky Blues' lead to eight points at the top of the table.

A boisterous 18,156-strong crowd -- the A-League's biggest in almost five years at McDonald Jones Stadium -- watched Ernie Merrick's entertainers prove they had the mettle to surge from wooden-spooners to champions.

Merrick praised an exceptional defensive performance. "I'd say the boys are pretty confident they can match it with anyone now," Merrick said.

Sydney FC coach Graham Arnold admitted his side lacked its customary crispness and execution. "That was the worst thing that happened to us, Roy getting sent off and them going down to 10 men," he said. "Then it becomes a bit of an attitude problem."

There was no clue of a Jets victory 10 minutes in when Buijs fell dramatically to the turf after an altercation with O'Donovan while contesting the ball. A four-minute VAR review eventually revealed the Irish striker had swung his closed fist across the Dutchman's face while holding onto his shoulder. Chris Beath red-carded him and the home crowd turned from former Jet David Carney to Buijs at every touch of the ball. 

Based on Sydney's ruthlessness, the numerical disadvantage should have killed off the contest. But the Newcastle defence -- boosted by the inclusion of Nigel Boogaard who re-injured his knee late -- settled in and Daniel Georgievski contained Adrian Mierzejewski.

The Sky Blues looked to capitalise and came close on 38 minutes when Milos Ninkovic brushed the side netting off Mierzejewski's misguided cross. Soon after they were down and Graham Arnold furiously watched Nikolai Topor-Stanley draw a relatively soft penalty from Buijs before Dimi Petratos converted with ease.

The Sky Blues returned fire soon after the break, Bobo rising to head home a wonderful Buijs free kick -- the Brazilian golden boot leader's 22nd goal this campaign. The ledger was level for just five minutes before Nabbout barrelled in another stunner from distance -- an angled 30-metre effort that sailed past a slow-reacting Andrew Redmayne into the far corner.

Nabbout's provider Petratos was outstanding throughout and hit the post late on the back of a solo weaving run through Sydney defenders.

As the Sky Blues started to turn the screws, Georgievski stuck out his chest to clear Mierzejewski's deflected shot off the goalline and save the game, before substitute Matt Simon inexplicably headed a corner over the bar.