Martin O'Neill has revealed an "overnight problem" meant Haissem Hassan did not start for Celtic against Rangers.
The winger was a notable absentee from the starting XI as he was instead amongst the substitutes away at Ibrox.
Hassan did come on in the second half but was prevented from starting due to the fact he "didn't get much sleep".
O'Neill confirmed the decision was based on that factor when he was quizzed on his team selection after the 3-0 loss at Ibrox as Celtic exited the Premier Sports Cup.
"Young Hassan had an overnight problem," said O'Neill. "And he didn't get much sleep in all honesty, so it was just a matter of not starting him because of that.
"That's the reason, really."