Analysis: The Sky Blues' high-profile attacking recruits have a genuine rival in the form of the homegrown forward, while the John van 't Schip has plenty of work still to doSydney FC coach Graham Arnold sounded a warning to veteran forwards Marc Janko, Shane Smeltz and Alex Brosque on Tuesday.
'Get fit or watch Corey Gameiro take your starting spot.'
After an injury-affected first season in sky blue, Gameiro is flying ahead of his second A-League campaign in the harbour city, scoring the opening goal for Sydney in their 3-1 FFA Cup win over Melbourne City to take his tally to seven in five games.
Janko, Smeltz and Brosque all missed the game with Arnold not interested in risking the trio - who are all in their 30s - as they work towards full fitness with a long season ahead.
But those forwards may need to demand more game time ahead of Sydney's A-League opener on October 11 or risk starting the campaign on the bench.
Gameiro's speed was a clear highlight of Sydney's victory, as he outpaced City goalkeeper Andrew Redmayne to give Arnold's men the lead in Ballarat.
With City dominating possession, Sydney focused on counter-attacking and Gameiro's pace and eye for goal made him a regular threat.
The 21-year-old could have wrapped up the win in regulation time but failed to get past Redmayne in a one-on-one situation, although the former Wellington Phoenix striker made up for it in extra time, getting away from City defender Jason Hoffman to win the penalty that put Sydney ahead.
"If he [Gameiro] keeps playing like that, he'll play every week," Arnold said in Ballarat.
"As I said to the players [on] day one, they have the opportunity to select themselves.
"If they perform well on the training pitch and in the games then they'll play. There's no favouritism, even if we've got marquee players in - they've got to be part of the team and they've got to perform as well - and Corey, so far, has been outstanding."
It was hard not to consider Gameiro as emblematic of the difference between the two teams at Morshead Park, as the former Fulham youth player regularly displayed the kind of quality and cutting edge in the final third that John van 't Schip's City lacked.
For all the money the City Football Group (CFG) - owners of Manchester City, Melbourne City, MLS expansion club New York City and Japan's Yokohama F. Marinos - have pumped into the team formerly known as Heart, the side van 't Schip sent out against Sydney looked frustratingly familiar.
This was last season's team minus Orlando Engelaar and Aziz Behich, now featuring Damien Duff and Aaron Mooy.
City controlled possession well in Ballarat, regularly winning the ball around the half-way line to keep the pressure on Arnold's side, but the hosts failed to break down Sydney's defence often enough to win the match.
While Duff and Mooy looked sharp, and marquee Robert Koren and New York-loanee David Villa will undoubtedly make a difference, there is still a sense City lack enough quality to be genuine A-League contenders.
Remember, Villa will only play 10 games before returning to the United States.
As Arnold prepares for a season where he knows Janko, Brosque, Smeltz, Gameiro and Bernie Ibini will all have to spend time on the bench, van 't Schip will still be forced to rely on the likes of the inconsistent Mate Dugandzic and the promising yet unproven James Brown and Ben Garuccio in the forward third.
What would van 't Schip give for a ready-made young Australian forward like Gameiro to complement the likes of Villa and Koren?
With one more import position and an Australian marquee spot still open in City's squad, CFG and van 't Schip should be looking to sign two top-line players before the A-League season begins.
Apart from Villa, City only have one lead striker in the squad in David Williams, who scored 12 goals in 26 matches last season, well above his overall A-League scoring ratio of less than one goal every four games.
Was that Williams' breakthrough campaign or an aberration? Only time will tell but either way, van 't Schip cannot afford only two options up front when one is set to leave after just 10 games.
A natural goal-scorer is a must, while van 't Schip should allocate the rest of his recruiting focus on a versatile, creative midfielder.
At times in Ballarat, Mooy seemed to be let down by incidents of poor control and passing of his fellow central midfielders - Massimo Murdocco and Nick Kalmar.
If City could sign another player like Duff, who can play both out wide and as a central midfielder, it would provide the Dutch coach with enough quality players to tweak his formation and personnel to account for injuries and fluctuations in form.
The hype surrounding City, Villa and Koren has ensured the Victorian rebranded outfit are most bookies' favourites to win the A-League but CFG's work is not complete if they are to make that a reality in their first season in charge.
The chequebook must come out again.