Ben Stokes returned to training on the eve of the third Test against the West Indies but England will delay a decision on his availability until after he is assessed.
There was clearer news on England's other two injury doubts on Friday, with Chris Woakes (knee) ruled out and wicketkeeper Ben Foakes (hand) declared available, but Stokes' fitness is the major concern.
Captain Joe Root suggested the all-rounder's bruised right heel was a result of the heavy burden he took with the ball during defeats in Barbados and Antigua – bowling just over 77 overs in baking conditions – but did not dismiss suggestions the injury was sustained while running on the beach during a fitness session.
"Whether it was before that or during that I'm not really sure to be honest," said Root.
"It's down to a huge amount of workload over the first two Tests. He woke up sore with his heel.
"He didn't practice yesterday to give himself another day to get right. He'll train today and have to see how he pulls up after that."
Stokes could conceivably play as a specialist batsmen if he is not ready to play a full part with the ball but should he be ruled out – and with England already 2-0 down going into the third Test, a conservative call could be made – the balance of the side would change considerably.
"He's an integral part of all three formats and has been for some time now and gives you great balance across the board," added Root.
"As we've seen in the recent past when he's not been around it can make a huge difference.
"Of course we want Ben fit and firing and ready to go as many times as possible. But it's so important he is able to do his job properly."