Bowling coach David Saker says Kevin Pietersen is facing a race against time to be fit for the Ashes series.
England's star batsman has been out of action since March with a knee injury and has already been ruled out of his country's home Test series against New Zealand and the ICC Champions Trophy.
It was thought the 32-year-old - who has scored 7,499 runs in 94 Test matches - would be fully recovered and ready to take part in the opening Ashes Test of this year, which begins at Trent Bridge on July 10.
However, England bowling coach David Saker cast doubt on Pietersen's availability for the first match against Australia after England wrapped up a 170-run win over New Zealand at Lord's on Sunday.
"We are all hopeful he will be back for the Ashes but we are still not sure on that. It would be great to get him back. He is a special player," he said.
"He seemed fine to me but he was just sitting next to me. I asked him if he thought he would be alright and he said he thinks he will. It was probably the only answer he could give.
"He doesn't know and until he knows he can run around and it doesn't flare up he can't have an answer on that. He was hopeful about the Ashes but said he is still not sure."
Saker went on to pay tribute to James Anderson - who became only the fourth Englishman in history to reach 300 Test wickets in the victory over New Zealand - labelling the seamer "the most skilful bowler in the world".
"I know (South Africa's) Dale Steyn is an outstanding bowler - but when you watch Jimmy and the way he went about things here, he has got more skills than Dale Steyn in his locker.
"Obviously Steyn is a little bit quicker - but when you watch Jimmy deliver those skills, it is just mind-blowing."
New Zealand have recalled veteran Daniel Vettori after left-arm spinner Bruce Martin was ruled out of the tour due to a calf strain.
Former Vettori is in now in contention to feature in the second Test at Headingley, starting on Friday, after last playing an international Test match against West Indies in July 2012.
The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of Cricket Australia
First Posted 21 May, 2013 2:31PM AEDT