Harris, the man-of-the-match as Australia wrapped up a 5-0 series clean sweep against England in Sydney on Sunday, said he needs a clean out of his right knee to remove fragments of floating bone.
"My knee is no different now than it was a month ago or six weeks ago," the veteran paceman said.
"Unless something really bad goes wrong, which I don't think it will, after Africa we've got enough time off to get it (knee) cleaned up and go from there."
Harris, who took 22 wickets in the Ashes series, revealed he considered having knee surgery that would have ruled him out of the fourth and fifth Tests against England.
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He said he had discussions with his surgeon before Christmas as he felt the effects of back-to-back second and third Tests in Adelaide and Perth.
He went on to play through the pain and earned man-of-the-match honours in Sydney with match figures of 8-61 as Australia completed a series whitewash.
"But I wanted to play five games. I wanted to be a part of it for the whole thing."
He said the floating bone caused by previous injuries has left him with little cartilage in his right knee, which swells up after a day's play.
But Harris insisted the condition will not keep him from bowling against the number one ranked South Africa.
At 34 and having been something of a late bloomer who debuted in Test cricket at 29, Harris knows he doesn't have long left in international cricket.
"It's as simple as that. And I want to be in this team as long as I can. (So) I'll put up with it.