Chelsea's Cole Palmer faces an extended period on the sidelines. AFP
The England midfielder has not played since Chelsea's 2-1 defeat at Manchester United on September 20 -- when he came off midway through the first half.
Maresca initially said he hoped Palmer, 23, would be back after this month's international break.
"I was wrong. Unfortunately, he needs to be out probably six more weeks. So, yes, this is the update," he said.
The Italian said he was confident that the forward would not require surgery.
"We try just to protect Cole as much as we can and the most important thing is that when he comes back he's fully recovered," he added.
Maresca, whose team face Nottingham Forest on Saturday, said replacing "one of the best players in the Premier League" was difficult.
"For sure, we need to find a different solution, we need to find different skills, because we don't have another player like Cole," he said. "Because Cole is unique."
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