John Kennedy has defended the zonal marking system used by Celtic, and insisted that their eyes light up when an opposing team uses man-to-man marking against the Hoops.

The Celtic defence has come under fire in recent weeks following the loss of crucial goals from set-pieces, most notably against Malmo and Aberdeen at the weekend.

But first-team coach Kennedy, who takes particular responsibility for drilling the Celtic backline, says that it is up to the team as a whole to clamp down on the slackness that has crept into their defensive play.

"I think we’ve made some costly errors," he said.

"We all know that and we all take responsibility for that.

"But it’s not a case of us pointing fingers at individuals. Team performances are what win you games.

"That applies defensively, everyone defending as a unit, as much as it does to creating chances at the other end.

"But, overall, defending has not been great.

“It’s the same thing that happens all the time, the debate kicks off whenever the zonal marking system concedes a goal.

“We’ve scored plenty against other teams that use man-to-man, we see it as a positive for us when other teams set up man-to-man against us. We find that we get more joy from it.

“In the past the system's worked. We’ve changed one or two little things but it’s not as tight as we would want it.

“We’ve conceded a goal, but we’ll make sure we fix it.”

Kennedy revealed that there is a chance that new signing Jozo Simunovic could be given the nod for the Europa League group game against Ajax in Amsterdam on Thursday night after impressing in training.

“He’s fit, he’s come in and trained well," Kennedy added.

"The weekend was too early for him after having very little time with the group, it would have been a big ask.

“But he’s training well and he’ll certainly travel with the group for Thursday."