England's preparation for the opening test against Pakistan has been thrown into disarray by a virus sweeping through the camp, which could delay the start of the match scheduled in Rawalpindi from Thursday.
Skipper Ben Stokes is among several England players who skipped Wednesday's optional training session after being laid low by the bug.
Former captain Joe Root was one of five players who did attend, and he later spoke at the pre-match news conference.
"As far as I'm aware, a few guys are not feeling 100 per cent," Root said. "I didn't feel great yesterday and I woke up a lot better today. So hopefully it's a 24-hour virus. Don't think it's like food poisoning or Covid or anything like that.
"We are trying to do absolutely everything right to make sure we are prepared for this game."
England have already named their starting 11, giving a test debut to Liam Livingstone and recalling Ben Duckett to open with Zak Crawley.
Root effectively ruled out leading England again should Stokes miss the match with illness.
"I don't think so ... Hopefully that's not even a conversation that we need to entertain," added the 31-year-old.
The Pakistan Cricket Board (PCB) said it was in touch with its English counterpart and was monitoring the situation.
"We are in discussions with the PCB regarding the start of the first test due to a viral infection within our camp," the England and Wales Cricket Board (ECB) tweeted.
England are also scheduled to play in Multan and Karachi in what is their first test tour of Pakistan since 2005.
They have hired a chef for the tour after receiving feedback from players who visited Pakistan in September-October for a seven-match T20 series.
Pakistan captain Babar Azam wished the English players a speedy recovery.
"I hope they get better soon. We'd like to face a full-strength England tomorrow."