England bowler James Anderson will miss the the fourth Test at Trent Bridge because of a side strain but is "hopeful" of returning for the fifth.
"It's not as serious as we thought at first. I'll be aiming to get myself ready in three weeks for the Oval," he told BBC Radio 5 live.
The fourth Test starts on 6 August with the fifth Test on 20 August.
An England and Wales Cricket Board statement said Anderson's availability for the final Test at The Oval would be "determined in due course".
After two compelling bowling displays by England, Anderson's omission from the fourth Test will come as a severe blow to the hosts.
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'I can come back stronger'
The Lancashire bowler took six wickets as Australia were all out for 136 in their first innings, before taking another as the tourists were reduced to 168-7 on day two. The home side wrapped up victory on day three to take a 2-1 series lead.
He was injured on his birthday after taking 10 scalps in the Ashes series so far, and will now miss the Trent Bridge Test which has been a happy hunting ground in previous years.
Anderson has taken 53 wickets in Nottingham, with Lord's the only Test venue where he has been more deadly with 75.
"It's a bit sore, I felt something on one of the deliveries," he added.
"It could be a number of things. It was on my 33rd birthday, after 12 years of professional cricket - that might have something to do with it.
"Injuries happen to fast bowlers. I've been very fortunate in the last few years that I've not had many so you've just got to take it on the chin. Hopefully I can come back stronger."
He joked: "I'll be trying to referee the football warm-ups in the morning, I spoke to Alastair Cook earlier and he said he'd like me to stick around."
Another Ashes twist
England team-mate Stuart Broad says bowling alongside Anderson at The Oval would be a boost.
"It is a big loss but Jimmy is more positive than when he left the field on Thursday," he told Sky Sports.
"He thought he had gone in the side but got back from the scan and was confident he would be OK for The Oval. That will be a big bonus."
The development has echoes of the injury suffered by Australian bowler Glenn McGrath, who hurt his ankle in the warm-up of the Edgbaston Test during the 2005 series in England.
Former England captain Michael Vaughan said: "There is always a twist in an Ashes series. Is Jimmy Anderson's injury that moment?"
Listen to Anderson's interview with BBC Radio 5 live.