Pace bowler James Anderson has been struggling with “a slight strain on his right leg”, the England and Wales Cricket Board (ECB) has said.
Anderson, 40, left the field on day one of Lancashire’s game against Somerset on Thursday and did not take part in the match. they finished with a draw on Sunday.
The ECB said Anderson’s fitness will be tested closer to the time of the Test against Ireland, starting on 1 June.
Anderson had a scan on the injury on Saturday.
England will name their squad for the game against Ireland at Lord’s this weekend. The five Test Ashes against Australia will begin on 16 June.
Lancashire head coach Glen Chapple earlier told BBC Radio Lancashire that Anderson’s injury was “not a big deal” and “we have to be confident about his recovery”.
Anderson, England’s leading wicket-taker, has been injured in the last two Ashes matches at home.
He bowled just four overs before suffering a calf problem in the first Test of 2019, which was drawn 2-2.
In 2015, he suffered a setback in the third Test as England won 3-2.
Any long-term problems for Anderson could add to the growing injury list in England’s top-flight department.
Captain Ben Stokes has previously expressed his desire to have eight fast bowlers for every Ashes Test, but in recent weeks injuries have affected Jofra Archer, Olly Stone and Brydon Carse.
Archer returned home from the Indian Premier League after resuming his long-term elbow problem, Stone suffered a hip injury while playing for Nottinghamshire and the unborn Carse suffered a side injury while playing for Durham.
In addition, Jamie Overton is in the early stages of his return from stress on his back.
However, of this quartet, only Overton played for England in their 10 out of 12 wins under captain Stokes and coach Brendon McCullum.
First-choice Ollie Robinson and Stuart Broad sat out the recent County Championship games for Sussex and Nottinghamshire respectively, while Mark Wood is missing the final stages of the IPL to attend the birth of his second child.
Recovery could come from the likes of Matthew Potts, who has been in good form for Durham, and Saqib Mahmood after recovering from a long-term injury.
England can also call on the likes of Chris Woakes and Sam Curran, both all-rounders with impressive records in domestic Tests.
