England's hopes of averting a 3-0 whitewash in the West Indies were hit when Ben Stokes emerged as a doubt for the third Test, with Ben Foakes and Chris Woakes also managing injuries.
If the worst happened and all three were ruled out of the game in St Lucia, which begins on Saturday, England would have just 12 fit players to choose from.
Stokes was present at training on Thursday, England's first full session since their three-day defeat in Antigua, but did not take part due to bruising on his right heel.
Foakes, who was hit on the hand by a Shannon Gabriel delivery last week and was unable to keep wicket in the second innings, was involved but has yet to be given the green light by medical staff.
Woakes is highly unlikely to make it as he manages a longstanding knee complaint.
England were keen not to make any early assessments, with another full day of preparation work ahead, but Stokes' ability to balance the side as a top-five batsman and reliable seam bowler makes any question mark overs his participation serious.
He would be considered as a specialist batsman even if he was unavailable to fulfil his duties with the ball, but England will give themselves more time to make a judgement.
Restructuring the side, or just the batting order, remain possible but with Adil Rashid having flown home to be with his pregnant wife options are limited.