Brendan Rodgers has bemoaned Celtic's poor defending as they drew 1-1 with FK Suduva in Thursday's Europa League playoff first leg at Marijampole's ARVI Futbolo Arena.
Rodgers, who has criticised several aspects of the Hoops' backline in recent games, was left to rue another example of lacklustre defending that left his side with a difficult job in the return leg.
"We gave away a soft goal," the Northern Irishman told reporters. "That is a real concern. We are not giving away many chances, but we don't defend the set-piece well enough.
"It is a European goal away from home and we go back next week to finish the job, but I look at the performance level and it wasn't quite how we wanted.
"We seem to lack concentration. That is a problem for us and our pride in terms of defending. It was a terrific ball into the box, but we have to defend it better than that. It gave them a bit of oxygen in the game that really our start should never have given them."
Celtic will contest the second leg at Parkhead next Thursday.