In keeping with the competition's overall trends for success, the A-League Grand Final is generally a contest in which older, more wizened heads take the lead. As with any high-stakes knockout game, experience and imperturbability matter.
But such circumstances are more what you'd call "guidelines" than actual rules. In 2011, for example, a teenage Mat Ryan took home the Joe Marston Medal as best afield in the Central Coast Mariners' losing effort against Brisbane Roar; and in 2004, 22-year-old Ahmed Elrich won the medal as his Parramatta Power lost to Perth Glory in the last NSL Grand Final.
And in what would be a fitting conclusion to a campaign that has been heralded as one of the best A-League seasons due to an influx of bold and exciting youth -- 107 of the 300 players deployed by coaches this season aged 21 years or under -- the 2021 grand final is shaping as one that may provide yet another fresh-faced protagonist with their star turn.
Melbourne City and Sydney FC were largely able to retain and add to a core of veteran talent this campaign, befitting their status as the A-League's most well-resourced and -run teams, but both were hit hard by call-ups to the Socceroos on the eve of the finals.
City, the 2020-21 premiers, lost midfielder Conor Metcalfe, defender Curtis Good and runaway Golden Boot-winning striker Jamie Maclaren; Graham Arnold's Socceroos call ups mean Sydney FC are without centre-back Ryan McGowan, goalkeeper Andrew Redmayne and fullback Rhyan Grant for the season's final day.
Grant, Sydney's longest-serving player, turned in a man-of-the-match performance in the 2019-20 grand final against City -- scoring a 100th-minute goal to secure a 1-0 extra-time victory.
The 13-time Socceroos player's duties in both a defensive and offensive capacity have been vital to the Harboursiders' success under Arnold and now Steve Corica, and his absence leaves an inevitable hole to be filled.
Enter 20-year-old left-back Joel King.
"I've been told by the coaches that I need to replace [Grant's] forward runs and all the attacking movements that he makes," King told ESPN.
"So I do try to get forward a bit more with him out, but, in saying that, I'm also trying to keep playing my own way and hopefully doing it well.
"A lot of the time in training I'm playing against him because he's on the right. He does teach me a lot with one-twos and forward runs and stuff. He's been great for me. I've learned a lot from him and, hopefully, I can play in a similar way to him against City."
King has become an ever-present figure on the left side of the Harboursiders' defence across the past two A-League campaigns, both in which it proved the league's most miserly. A shining example of what can happen when a club backs young players with consistent opportunities, he logged 98% of minutes available this season and on Wednesday was named the A-League's Young Player of the Year -- becoming the first Sydney prospect to receive the honour.
"I think mainly I've been a bit more confident in myself getting forward," King said of his 2020-21 season.
"I'm backing myself to try things. Last year I was a bit reserved and didn't want to make mistakes, but this year I'm just trying things... most of the time they don't come off but when they do they've been good."
- Lynch: City, Sydney square off in fitting A-League Grand Final
Going off minutes played this season, King will be the second-most experienced player at the back for Corica on Sunday; only iron man Alex Wilkinson has played more. Likely to start alongside them in the wake of the Socceroos call-ups will be Paulo Retre at right-back, Ben Warland at centre-back, and, in just his eighth senior game for Sydney, goalkeeper Tom Heward-Belle.
Locked in what was a fierce battle for second, Corica resisted the urge to rotate his squad to prepare for finals after being informed of the looming Socceroos absences -- a move that paid off as Sydney finished the regular season on a five-game winning run.
But with the departure of Redmayne looming, and the goalkeeping position perhaps the most difficult to fill from a standing start, Heward-Belle was sent down to Sydney's NPL NSW side in late May.
"As a young goalkeeper, you need to be playing, getting match minutes and seeing those scenarios play out in front of you," Redmayne told ESPN.
"I think the minutes Tommy got in NPL have held him in great stead -- the performance in the semifinal showed that.
"He's a bit like me, in a way. He's had to bide his time, floating around as a No. 2 and spending a lot of time on the bench, which is extremely hard -- I know that.
"I don't think [waiting on the bench is] tough, I think it's mentally excruciating. It's really hard because I think you can see from Tommy's performances he's more than capable of playing in the A-League; he just needs an opportunity to play."
While the Sky Blues have had to search for defensive reinforcement, the opposite holds true for City.
Not only will coach Patrick Kisnorbo's side turn to youth in an effort to replace the 25 goals of Maclaren but also, potentially, Craig Noone and Andrew Nabbout -- who both missed the semifinal win over Macarthur with injuries.
"Everyone talks about the front three of Maclaren, Nabbout and Noone and then we come to a semifinal and we've got two youngsters who have got a goal and an assist each and played 90 minutes," City Director of Football Michael Petrillo told ESPN.
The youngsters referenced are 21-year-old Stefan Colakovski and 19-year-old Marco Tilio, who proved the heroes as Melbourne City defeated Macarthur 2-0 to make the grand final.
"I see little glimpses of myself when I was 19 in them," Maclaren said of the pair.
"After every session, I take them to the other side of the pitch and work with them, Conor and Naoki Tsubaki and do some finishing drills, and we work on different aspects of where the ball is going to fall.
"They're still young boys, they've got a lot to learn as [Kisnorbo] said, but at the same time they want to learn.
"It's not a challenge for me to pull them up after training sessions to work on finishing. They come with me straight away. I see great things with them."
Moving from Sydney to City last offseason, Tilio has provided two goals and five assists in 2020-21 and emerged as one of the A-League's most exciting prospects.
"I pretty much came over just for opportunities," Tilio told ESPN. "I knew coming over and working behind such quality players that I would eventually get my chance -- not knowing about call-ups or injuries -- but I knew City had faith in me and would give me opportunities to play.
"Physically and mentally it's been tough this season. Physically putting the output on the field that is required from this team, getting up to that standard was quite tough.
"And I guess mentally knowing that I could be good enough to play in this team."
Petrillo said "it would said have been the easiest decision to stay at Sydney, the comfort of [Tilio's] own home and the club he'd been around".
"The hardest decision was to get out of his comfort zone and come down to City and fight for a spot. I suppose it speaks to his character and his ambition to be the best player he can be."
For Colakovski, Sunday offers the chance to fulfil a childhood dream.
Beloved by City fans because of it, he grew up a Melbourne Heart fan -- he was in the stands for their first A-League game against Central Coast Mariners -- and eventually earned his way into their academy.
"[Colakovski] went through a year or two of constant injuries, be they soft tissue or otherwise, and that sort of set him back," Petrillo said.
"But we always thought Stef had something special as well. We needed to give him a chance to recover."
Overcoming numerous maladies -- including a badly torn ACL -- the former Pascoe Vale and Essendon Royals junior was overlooked for a scholarship contract until former coach Erick Momaberts took a shine to him.
Impressing in his debut against Wellington in late 2019, he received a scholarship deal that was soon upgraded to a fully professional one.
He has since largely operated at the City Football Academy as Maclaren's understudy, able to play as a nine or out wide.
"Maclaren's Maclaren," Colakovski told ESPN. "The guy scores goals for fun and our whole front three was unbelievable this season.
"I wasn't happy to just be an impact player and come off the bench, but I knew that was my role this season. Even just being able to come on in the grand final I would have been happy.
"But now obviously an opportunity has presented itself and I hope I've put myself out there to start. That's not something I would have thought of at the start of the season.
"I'm so happy that the final is going to be in Melbourne. Obviously to have that 15k fans.
"But, man, I've watched the club since the beginning, since that Central Coast game, our first ever game.
"We haven't seen that much success in terms of silverware, so to be able to be part of the team that possibly is one of the greatest City teams, if we do win, it would be huge."