(Reuters) -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.
Captain 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.
"As far as I'm aware, a few guys are not feeling 100%," Root told a news conference.
"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 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 added late on Wednesday that the two unanimously agreed to delay the decision on the commencement of the test until 7.30 a.m local time (0230 GMT) on Thursday.
"The two boards also agreed, subject to the England players not recovering well enough to take the field on Thursday, then the test will commence on Friday and will be a five-day match," the PCB said in a statement.
"In this scenario, the schedule of the second test in Multan and the third test in Karachi will remain unaffected and will be played as per original schedule -- Dec. 9-13 and Dec. 17-21.
England are on 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."
(Reporting by Amlan Chakraborty in New Delhi; additional reporting by Shrivathsa Sridhar in Bengaluru; Editing by Peter Rutherford, Hugh Lawson, Alison Williams and Ed Osmond)