As the club raked over the controversial aftermath of Brown's red card against Barcelona for kicking Neymar, Kayal insisted team spirit can ensure Celtic qualify from Group H.
The Israeli said: "We win and lose as a team and that's all there is to it. If we have to play Ajax without Scott then we will still be confident that we can in the games. You have seen the way we have played against AC Milan and Barcelona.
"We have taken no points, but we have been very unlucky. Scott is a great player, he is our captain and he is respected by everyone in the dressing room.
"But at this club there are good players in every position and if he is banned for the game then we have to get on with it.
"We will fight on. We are only ever thinking of the next game and if we can take three points from that then it could open the group up again. We are ready.
"Our confidence is good. We are not a team that go into hiding and I think we will show that when we play Ajax. There is still a lot of football to be played in this group."
Confident Kayal issued his battle cry as Celtic get set to appeal Brown's one-match ban ban, which could be extended to three, after Tuesday night's 1-0 defeat.
Neil Lennon's side are fighting for their lives now in Group H and the double-header against Ajax on October 22 and November 6 assuming win-or-bust significance Ajax are a point better off than Celtic after drawing with AC Milan.
Kayal, though, has maintained Celtic have not given up hope of getting out of the group despite their disappointing start.
"People always said it would be Barcelona and AC Milan who progressed, but you never know in football - and we still think we can open things up if we beat Ajax," he said.
"We don't want to think too far ahead, but we haven't set our sights on third place.
"We want to take as many points as we can from our four remaining games and we will see where we are after that."