Captain Alastair Cook admits it will be a gamble if England recall James Anderson for the second Test against South Africa in Cape Town.
Anderson missed England's handsome win in Durban with a calf strain but is desperate to return to action at Newlands.
He has done everything the medical team have asked of him, and suffered no major setbacks, but the fact he has sent down just five competitive overs since arriving in the country remains a concern.
South Africa's key bowler, Dale Steyn, broke down in the middle of the series opener following an injury lay-off of his own and England will be eager not to make the same mistake.
Anderson may well be under-prepared for the rigours of a five-day Test in sweltering conditions but the temptation to rush back the most experienced bowler in the squad, and the nation's record wicket-taker, remains strong.
"It's fair to say that the eleven who played in Durban did a pretty good job, but when you've got Jimmy and his wickets in the background, if he's fit to go, then he'll play," said Cook on the eve of the match.
"But it's an interesting call because of how many overs he's bowled so far on this tour - not a huge amount - and the conditions will be a tough Test for all of us.
"We'll have a good chat in the changing room and see how he feels. We have to be really careful with heart and head.
"He's desperate to play but we just have to make sure it's the right decision for him.
"If he's fit and ready and confident, then he'll be opening the bowling but we don't want to hinder ourselves and have an injury caused that we could have prevented.
"Obviously there will be a bit of a risk about it."