Oxlade-Chamberlain had a serious injury during pre-season, according to the boss.
He picked up the injury during the game against Crystal Palace.
The goalkeeper won't return to fitness for two, three weeks.
It will take more. It's a serious injury and will take a long time to heal.
We don't like this word, we hate the injury, but Ox was the one, and it happens from time to time.
Oxlade-Chamerlain had a knee problem that kept him out of action for one year.
While on international duty with the Republic of Ireland, he picked up an injury.
After the international game, Caoimhin felt something and the medical department at the airport told him it was fine and he would be fine after the holiday.
First training session he felt it again. I think he will be okay after we checked it and it wasn't great.
The Community Shield will be held at King Power Stadium.