The prolific Argentine came on as a second-half substitute in a 3-0 victory against West Brom on Monday, his side's first game of the new Premier League season, having returned late to pre-season training as a result of his participation in the Copa America over the summer.
Still needing time to recapture full match fitness, Aguero says that he may continue to play only as an impact substitute against Jose Mourinho's reigning champions.
"Whether I start or not remains to be seen," the former Atletico Madrid forward told City's official website.
"I'm trying to get there and be in top condition but arriving for pre-season later, having taken part in the Copa America with Argentina, means I need some additional time.
"With the whole season in mind, what matters the most is that I get in top form and don't take any risks."
Chelsea finished eight points clear of second-placed City last season but Aguero expects a more dramatic title race this time around.
"One thing you can say about the Premier League is that, every year, it gets better," he added. "Once again, many teams have made very important additions and that means there's no single rival for us this season.
"It'd be very naive to think that Chelsea will be the only team competing for the top position - there will be many of us and each one will challenge in their own style.
"We'll stay hungry for glory, we'll do our jobs, we'll win all we possibly can and see where that takes us."
