Graham Onions has a hamstring strain and was unable to take part in England practice on Wednesday morning, on the eve of the first Investec Test against South Africa at The Oval.
Onions, included in England's 13-man squad as an extra pace bowling option, joined his team-mates for warm-ups but was not involved in this morning's net practice.
He has not yet been ruled out of contention to play on Thursday, but must be considered a significant doubt. The Durham bowler was an outsider to be included as England's third seamer, in any case, with incumbent Tim Bresnan and also Steven Finn likelier choices in most minds.
There was other business to be settled for England on Wednesday afternoon, with their 30-man preliminary ICC World Twenty20 squad set to be announced.
The list will be notable for the absence or otherwise of Kevin Pietersen, whose on-off limited-overs retirement will probably depend on whether he can reach a compromise deal with the England and Wales Cricket Board in time to play in the World Twenty20 in Sri Lanka in September.