Celtic boss Ronny Deila has warned his side that they will need to improve for their Champions League qualifier after losing 5-3 in a friendly to Dukla Prague.
The Scottish champions were beaten by the Czechs at St Mirren Park on Saturday, with Marek Hanousek netting a hat-trick for the visitors.
Celtic host Icelandic outfit Stjarnan in the first leg of their qualifying tie on July 15, and Deila concedes that they will need to play a lot better in that match than they did against Dukla.
"We can't play like this or we will get big problems whoever we play, if it's against Stjarnan or St Johnstone or Barcelona," he is quoted as saying by Sky Sports News. "It was a good test for us. They are a good team. I don't think we had a good performance but it's early. We have been back four days with 60% of the team."
Celtic begin the defence of their Scottish Premiership title at home to Ross County on August 1.
