England coach Andy Flower revealed injury worries about two pivotal players - Matt Prior is the other, and will have a scan on his left calf - at the end of the tourists' rain-wrecked draw against Australia A in Hobart.
Pietersen's previous problems in his knee, however, mean there are sure to be heightened concerns about his fitness in particular for the Ashes opener in Brisbane on November 21 - a match which should be the mercurial batsman's 100th Test.
Pietersen was out for three months earlier this year with the same injury, missing the final Test of England's drawn series in New Zealand, the Indian Premier League, the start of the domestic season, two Tests, three one-day internationals against the Kiwis at home and then the Champions Trophy.
He returned in the nick of time for the start of last summer's Ashes, which England won 3-0 to put them on course for a fourth successive series win against Australia and Pietersen himself the fifth of his career.
First, though, the 33-year-old will leave his team-mates as they travel to Sydney on Sunday for their final warm-up match and fly instead to Melbourne for urgent medical treatment and a prognosis.
"Kevin has had a slight recurrence of that knee issue, and he'll be going to Melbourne for a scan and a cortisone injection tomorrow (Sunday) morning - so he won't be travelling with the rest of the team," said Flower.
"I don't think it's going to be a huge issue. He's had a couple of these injections before, and they've been successful.
"They've quietened the problem down, and it's obviously an ongoing issue for him.
"They have been successful, and we anticipate this one being successful and anticipate him playing a full part in the Ashes tour."
England still hope, in fact, that Pietersen - who could make only eight in his first innings of the winter on Saturday as England declared on 430 for seven - will be fit for their match against an Australian Invitational XI at the SCG.
"He felt it in the first day (here), I think," the coach added.
"We anticipate him playing in the Sydney game.
"We're doing the jab tomorrow, so he's got a little bit of time for the jab to work before we train on Tuesday."
Flower estimates the effects of the cortisone injection will last "months".
But Pietersen is thought to have come close to requiring surgery on the joint previously - and regardless of England's public optimism, these will be tense times for the tourists.
There appears to be a similar degree of anxiety over Prior, a pivotal mainstay in England's last three successful Ashes series and Alastair Cook's vice-captain too.
Flower said: "He is a concern. He's tweaked something in his calf.
"We're not sure of the extent of the injury as yet ... he will obviously need a scan."
The coach was heartened that Prior had little time to exacerbate the injury - suffered while batting with Joe Root (58no) - because he was out very soon after first feeling discomfort.
"He didn't make it much worse - he was off soon after he tweaked it," he said.
"As soon as we know more about it, we'll tell you.
"He'll go for a scan pretty much as soon as possible."
There is hope rather than definite expectation about Prior's recovery.
"I don't think it's anything too serious, and shouldn't keep him out of the first Test," said Flower.
"But let's just scan it, and then we can give some more information.
"Just from what I've seen, I would imagine he'd be okay for that first Test.
"But I hope I'm not speaking out of turn there.
"He's moving around okay ... I don't think it's linked to the Achilles problem [he has had in the past]."
As for whether Prior could yet even play in Sydney next week, he added: "We don't know yet. It's possible.
"His experience is very valuable to us. However, if he's injured and unavailable, (Jonny) Bairstow will step in.
"He is a very good young cricketer, and will bring his own qualities to the England side."