There didn't seem to be much positive about their FFA Cup final defeat at the time, but the Sky Blues' loss to Melbourne City is now regarded as a blessing in disguise after teaching some of their younger players how to stave-off jitters and remain composed in high-pressure matches.

If everything goes according to Sydney's plan, the November 30 cup final was a dress rehearsal for what they hope will be their second grand final appearance in three seasons and an early lesson on how to keep calm when so much is on the line.

Midfielder Brandon O'Neill, 23, admitted he had to overcome initial stage fright in the decider at AAMI Park in what was until now, the most cut-throat match of his career.

While a Tim Cahill header ended Sydney's hopes of clinching an unprecedented domestic treble, the Sky Blues regained their composure and felt they were unfortunate not to have equalised to send the match into extra-time. Knowing how to get back to their game plan amid such desperation has created a sense of calm and confidence for O'Neill heading into next weekend's sudden-death finals match at Allianz Stadium.

"I learnt about where I'm at as a player both mentally and physically," O'Neill said. "That was my first ever final and it was a real test of our character. We went one goal behind and looking back at it, we didn't stop fighting in that game. As a young player you go to Melbourne, you have a different scenario and it tests your nerve.

"Now I know what it's going to be like in this final stage. We're thankful now we have two home games, we have our crowd, our people cheering us on. It all boils down to doing what we've done in the last 27 weeks."

It was one of only two defeats in all competitions for Sydney FC this season and served as lingering motivation for the remainder of their campaign, one that finished with the premiers' plate and a flurry of records.

"It was a great stepping stone to what actually made us champions this season. That was the fire in the belly that spurred us on during the year. Preparing for that game mentally has prepared us to be where we are today, just two massive games left," O'Neill said. "Anything [we learnt] from that FFA Cup game was never to rest, never to be happy with a performance and always want three or four goals instead of one or two. It was about putting away teams early."

The players don't believe they've been hampered by the week's rest and quashed any suggestions of the break disrupting their momentum heading into next week's game. Sydney practiced with an intra-club, in-house match played behind closed doors at their training base on Friday and O'Neill is raring to go.

"Heading into the finals, the lads couldn't be any more positive and any more confident," O'Neill said. "It was great to have a taste of it in the FFA Cup final and I have an expectation now and I know what to expect in finals football. It's a bit different to league football. It's more cut-throat and there is a lot more on the line."