James Anderson: England seamer to miss rest of Lancashire game with calf injury
England's James Anderson was forced off with tightness in his right calf on day three of Lancashire's County Championship game against Durham.
The 36-year-old pulled up while running in to bowl and tried three times to complete the over before going off.
The seamer will play no further part in the match at Sedbergh School.
England play a Test match against Ireland at Lord's starting on 24 July, before the home Ashes series against Australia gets under way on 1 August.
Anderson has taken an English record 575 wickets in 148 Tests for his country, to stand fourth on all the time-list behind only Muttiah Muralitharan, Shane Warne and Anil Kumble.
He claimed his 950th first-class wicket on Monday, having now taken 30 in six Championship matches so far this season, at an average of just 9.37, from 159.4 overs.
Following the close of play on Tuesday evening, Lancs assistant head coach Mark Chilton told BBC Radio Lancashire: "Jimmy has been sat with an ice pack on but he seems fine and reasonably jovial.
"With any bowler if they feel something abnormal we would much rather they came off and get assessed rather than take it a step too far.
"He has been very well managed with regards to his bowling loads and his overs. That has been managed expertly right throughout the season."
Injury 'hugely concerning for England'
BBC Radio Lancashire commentator Scott Read at Sedbergh School
With just a month to go until the first Ashes Test, the sight of Anderson leaving the field of play, unable to complete his over, will be hugely concerning for England.
Anderson tried, unsuccessfully, three times to run in and bowl - the third time, he lasted just a couple of paces.
He appeared to try to stretch out his right leg before deciding to retreat to the dressing room in order to prevent any further damage.