Injured captain Alex Brosque and suspended quartet David Carney, Jacques Faty, Seb Ryall and Rhyan Grant - may be missing from the squad, but Janjetovic said that right now it is about the attitude and belief of the players who are available.
The 28 year-old said the team was "buzzing" with excitement coming off the back of Wednesday night's 2-1 win over Asian powerhouses Guangzhou Evergrande and going into Saturday night's game against City at AAMI Park.
Much has been made of Sydney's indifferent form in the A-League recently, but City have had their ups and downs of late as well.
"We haven't won in a while in the A-League and people have been saying we've disappeared into the background," Janjetovic said. "But we've had a fair few injuries and quick turnarounds to deal with, so I think the feeling after beating such a big team as Guanghzou has given everyone confidence.
"When you haven't won for a while you can lose that winning mentality, that winning feeling, but I think everyone here now believes we can come out and do something on Saturday night.
"Everyone was buzzing in the change-room after the game on Wednesday night. It was a great result not only for the team, but for every individual. We all did our jobs and got a great reward at the end, so we're going to go into the game against Melbourne City confident.
"City have been having a bit of trouble lately and they want to win more games, but hopefully we can go there and give them a bit more trouble and something to think about.
"Everyone has their little slumps and you expect that during the season, but when you get the mix of players and the balance right you can come out on top and we aim to be heading towards the finals in good form."
Janjetovic said the players were quickly finding out what works best for them in terms of handling the short turnarounds from weekend to midweek games and back again.
"We've had a few games back-to-back now and the way the boys recovered for the Guangzhou game and the way we quickly got things settled on the field showed we're doing it right," he said.
"We played to our structure and that was the main thing. The ACL is an awesome competition. Teams play each other week in, week out in the A-League and everyone knows you and how you play, but it's a bit different with the teams from Asia.
"There is that surprise element to the game and that adds to the excitement. A win is good any time, but to win against the giants of Asia is huge and hopefully that momentum will slide into the next couple of games in the A-League for us."
Janjetovic, who was one of the heroes of the ACL win with a crucial penalty save, said the aim for Sydney now was to make a run from sixth place in the A-League back into the top two or three.
"It's the current Sydney team's first time playing in the Asian Champions League, so everyone is finding their own balance and how to handle the period between games with recovery and that sort of thing," he said.
"Everyone's got a different preparation. It was tough leading into Wednesday's game with injuries, but now it feels like we've kick-started our season again.
"There are only a few points between the top few teams in the A-League and a couple of wins and you're right back in the mix for first, second, third on the ladder, so there's no reason we can't get back up there in the last six rounds."