Celtic defender Efe Ambrose has insisted that his side must remain focused until the final whistle.

The Glasgow giants have conceded late goals against Barcelona and Dundee United in recent weeks, but it was the defeat in the Nou Camp that has had a lasting effect on the 24-year-old.

Ambrose said: "The last game was hell for us in the Nou Camp because we fought until the last minute before Barcelona scored their winner. It's very worrying that we've lost our concentration so late in these matches.

"In the Nou Camp, it was the 94th minute and then at Tannadice it was two late goals in two minutes, so we need to sort that out.

"We've talked about it with the manager and we know what we need to do - and we will do it."

Celtic host Barcelona on Wednesday night.