James Anderson will have a scan on his calf after bowling just four overs in the first session of the Ashes.
The England seamer conceded a solitary run from a probing new-ball spell at Edgbaston, as the hosts reduced Australia to 83-3 at lunch.
However, the availability of England's all-time leading wicket-taker for the rest of the match is in question after the ECB confirmed he is suffering from tightness in his right calf.
Anderson injured the same muscle on July 2 playing for Lancashire against Durham, with the problem keeping him out of action until this week.
Stuart Broad took 2-17 and Chris Woakes 1-17 in a strong start for England, although the decision to pick Anderson ahead of the of Sam Curran, Olly Stone and Jofra Archer – the seam trio omitted from the hosts' 14-man squad - is likely to be called into question if he is unable to return.
Update: Jimmy Anderson has tightness to his right calf and will have a scan this afternoon. A further update will be given later today.
He felt tightness at the end of his fourth over.#Ashes pic.twitter.com/bQrrECkwOf
— England Cricket (@englandcricket) August 1, 2019