Arsenal manager Arsene Wenger says Mohamed Elneny was substituted before half-time of Wednesday's EFL Cup defeat to Southampton because he was struggling with illness.
Elneny was withdrawn in place of Granit Xhaka after 43 minutes of the quarter-final contest at Emirates Stadium, which Saints won 2-0 thanks to goals from Jordy Clasie and Ryan Bertrand.
And Wenger revealed after the game that the Egypt midfielder had been unwell, but put himself forward to play.
"He was sick before the game. He decided he felt well enough," Wenger said.
"I could see after five or 10 minutes that he was not right. He has no medical injury problem, but he has diarrhea or a stomach problem."
The Gunners boss also declined to provide excuses for the defeat to the Saints, insisting that their opponents were the better side over the 90 minutes.
He added: "There are no excuses and we can only say Southampton were better than us.
"We had a disappointing performance, especially in the first half. We were not good enough defensively and we gave cheap goals away.
"We were not incisive enough. They defended deep and were sharper and fitter than us. With a two-goal advantage they defended very well."