A virus has swept through England's squad which could result in their first Test match in Pakistan for 17 years being delayed for 24 hours.
Around 14 members of the touring party are affected by the illness, including captain Ben Stokes, casting a shadow over the highly-anticipated match in Rawalpindi.
The Pakistan Cricket Board said on Wednesday that it was discussing next steps with the England and Wales Cricket Board.
A final decision is due to be made on Thursday morning – the first scheduled day of the Test match.
England tweeted: “We are in discussions with the PCB regarding the start of the first Test due to a viral infection within our camp.”
All of the squad will be monitored continuously overnight, but a decision is not expected until the morning.
Joe Root addressed the media in place of captain Stokes but the former captain remained upbeat over the chances of the game going ahead.
“It's such a monumental tour and important series for so many reasons,” Root said. “We've waited 17 years to come to Pakistan to play a Test match. It means waiting another day, is that the worst thing in the world?
“We're all desperate to play this game and we know how important it is to the fans of Pakistan and their team as well.
“As far as I’m aware, there are a few guys not feeling 100 per cent. I didn’t feel great yesterday but I woke up better today so hopefully it’s just a 24-hour virus and I don’t think it’s food poisoning or Covid or anything like that.
“I think it’s just one of those things that we’ve unfortunately picked up as a group – we’ve tried to do absolutely everything.
“We’ve prepared really well for this game and sometimes life throws things at you but we’ll do everything we can to be right tomorrow and be right and ready to go.”
Mark Wood missed training on Tuesday through illness with other members reporting symptoms later on in the day.
A training session on Wednesday morning was made optional before the illness struck but head coach Brendon McCullum was on hand to put Harry Brook, Zak Crawley, Keaton Jennings, Ollie Pope and Root through their paces in the nets.
Stokes had named his nominal starting XI for the match, including handing a debut to Liam Livingstone and a first Test recall since 2016 for Ben Duckett, but his plans could be forced to change due to the illness.