"Indian Wells, I hope to be back. Right now, there's no guarantee. I will do tests and see what the doctors say."
Federer's withdrawal leaves Murray as the highest-ranked player in the top half of the draw, and the Scot will open his campaign against Russian qualifier Igor Kunitsyn.
Murray has been off the circuit for almost a month after reaching the Australian Open final in January, recuperating after his defeat by Federer.
"I don't want to be going over to Indian Wells, Miami with niggles," said Murray. "By the end of that month you're undoubtedly going to be hurting so you don't want to go into the tournaments already sore.
"So I need to make sure that I take enough time after, like in Australia. I need to make sure that I'm fresh. My back was sore, my knee was hurting, my hip. After Australia you need to make sure that you got those things right.
"A lot of it is through tiredness, but the sport is such a physical one. Your body takes such a pounding and over the course of the two weeks you're hitting, playing, doing interviews as well. I'm not complaining about it, but it does take away some energy.
"You need to make sure you get away from it and just refresh our mind and come back feeling right for all the tournaments," added the 22-year-old Scot.
"That's the difference, the change that I've made in my mentality over the last six months or so. I want to go into all of the slams feeling right, because last year that wasn't the case. And I don't want that to happen again."
Croatia's Marin Cilic is a potential semi-final opponent for Murray in what would be a repeat of their Australian Open encounter at the same stage, which the Briton won in straight sets.
The first round gets under way on Monday, with Murray against Kunitsyn the late match after defending champion Djokovic takes on Guillermo Garcia-Lopez at 1500 GMT.
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