Celtic manager Ronny Deila knows his side must improve if they are to qualify for the Champions League group stage this season.

The Bhoys defeated Icelandic side Stjarnan 6-1 on aggregate following a 4-1 second leg victory in Reykjavík on Wednesday to make it through to the third qualifying round.

The Glasgow giants held a two-goal advantage going into the match at the Stjörnuvöllur, but that lead was quickly halved after the minnows scored a surprise goal in the sixth minute of the game through Olafur Karl Finsen.

The Hoops managed to regroup and took control of the tie once again when Nir Bitton scored in the 33rd minute before second-half goals from Charlie Mulgrew, Leigh Griffiths and Stefan Johansen sealed the Scottish side their place in the next round.

Celtic will now face Azerbaijani champions Qarabag in their next match after they defeated Montenegrin outfit Rudar Pljevlja and Deila knows his team will have to improve against the eastern European side.

He said: “They are a good team. I saw them play the first leg at home against the team from Montenegro and it is a big step up from what we have met here.”

The first leg will take place at Celtic Park next week and Deila is looking forward to the encounter as his players bid to reach the group stage of Europe’s premier club competition for the first time since 2013.

He added: “We didn’t want to concede an early goal but it happens sometimes. We came back and 4-1 is a positive result and I am looking forward to the next round.”

The Hoops are 1001.00 to secure their first European crown since 1967.