"From the reports we have had," Illingworth said, "it will set him back two weeks if he plays. It is a tough decision, but I know what I would do. I would put England first."
If Gough is fit enough to play he will not find it easy to pull out of such a big game against Yorkshire's fiercest rivals, particularly as the plum tie of the round is expected to attract a near full house.
For Lancashire Peter Martin, another pace bowler hoping to regain his England place, is standing by for a return in case Glen Chapple's troublesome knee rules him out.
Their captain, Mike Watkinson, back from his successful Test debut at Old Trafford and celebrating his 34th birthday today, said: "Peter wants to play but we shall not be taking any undue risk with him."
Warwickshire, meanwhile, are seeking a repeat of last summer's remarkable treble. They visit Derbyshire where England's Dominic Cork will be one of the main obstacles to their hopes of further success in the one trophy that got away from them last time.
Warwickshire will be without the all-rounder Paul Smith, who has a broken finger in the right hand and a hairline fracture of the left. Graeme Welch, Ashley Giles and Micky Bell are fighting it out to replace him.
Glamorgan will be without Roland Lefebvre at Cardiff, where they take on Middlesex. And at Bristol, the opener Dean Hodgson and the veteran seamer Kevin Cooper look likely to be drafted into the Gloucestershire team for the visit of Northamptonshire, who have to choose between Tony Penberthy and Jeremy Snape as a replacement for Neil Mallender, who has a knee injury.Reuse content