Celtic manager Ronny Deila admitted his side need to work on defending set plays after a goal conceded from a corner saw them miss out on victory against Fenerbahce.
Brazilian striker Fernandao took advantage of an Efe Ambrose error just before half time to make it 2-1, after Leigh Griffiths and Kris Commons had given Celtic a 2-0 lead in their Europa League Group A clash in Glasgow.
Ambrose was at fault again when Fernandao was allowed to jump unchallenged to head home Nani’s corner three minutes after the break, and Deila acknowledged that set plays are causing problems for his defence.
He said: "We played well in the first half. We started off a little bit nervous, but after 10 to 15 minutes we got more comfortable on the ball, started to play and get crosses in, and we created two very nice goals and I think we had control of the game.
"Then we made a stupid mistake - as happens in football - but you get punished hard when you are in Europe.
"We started the second half poorly and they got to 2-2 from a set play - that's something we need to sort out."
He added: "We finished the game better, but we didn't create enough big chances. I'm a little bit disappointed, but I'm happy with the effort the boys put in. They worked really hard, and we had a good chance to win."
Despite seeing the lead slip away, Celtic captain Scott Brown relished the challenge of playing another big European team from a group that also includes Ajax and Molde.
He said: "It's mentally draining [losing the lead] but we still fought on. We created a few more chances and I think we've played really well yet again at home.
"It's a great group for us, against hard teams.
"In the second half they played two up front. They changed their game-plan a little bit and we had to kick it long and win second balls, and we managed to do that well.
"We still managed to get the ball down and play as well as we possibly could, but it just wasn't to be."
