Medical experts are baffled by a groin injury which has sidelined Tyrone captain Brian Dooher.
Dooher is a major doubt for his side's All-Ireland SFC quarter-final on Saturday week, but manager Mickey Harte is still hoping his skipper will play some part.
'There's a difficulty in determining the nature of the injury,' said Harte.
'Brian has had various tests, none of which have shown a reason for the problem.
'He's ruled out a number of things and he's still a few tests to go through to see if he can find the cause of the pain.'
Dooher is one of four key Tyrone attackers currently battling against injury ahead of the August 4 clash with opponents yet to be determined by next weekend's draw.
Owen Mulligan is struggling with a back problem, Gerard Cavlan has a hamstring tear, and Stephen O’Neill is suffering from tendonitis in a knee.
