The defender was substituted for Aleks Zinchenko during the interval of the 2-0 defeat.
"Kyle could not continue in the second half," he said.
"The first half all the dangerous situations we created were from Joao. On the left side he was the most brilliant player on the team.
"Kyle had an infection in his stomach. He didn't train so well, he lost a lot of weight and he made an incredible effort to play because we needed fast players with the problems we had backwards because we knew we needed to make the build up with three in the back and not four. But at half-time he said he didn't feel good so we make the change."