Manager Ronny Deila admits Celtic must improve on a shaky opening in Iceland if they are to negotiate their next Champions League qualifying hurdle.
Having beaten part-timers Stjarnan 6-1 on aggregate, Qarabag are Celtic's next European opponents.
"They are a good team," said Deila of the Azerbaijan outfit. "It is a big step up from what we have met here.
"We need to improve. We were a bit sloppy at the start but we got the goal and we knew things were happening."
Celtic travelled to Iceland with a 2-0 advantage from the first leg in Glasgow but found themselves under pressure after only six minutes when Olafur Karl Finsen shot the home side in front.
Nir Bitton levelled with a 32nd-minute header and further goals from Charlie Mulgrew, Leigh Griffiths and Stefan Johansen made it 4-1 on the night.
"In the second half there was only one team on the pitch and we won quite easily," added Deila.
"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."
Bitton is sure Celtic will be in better shape when they host Qarabag in the first leg of the third qualifying round tie on 29 July.
|Who are Qarabag?|
|Azerbaijan Premier League champions||Did league and cup double last season|
|Star man: Reynaldo, 25-year-old Brazilian striker||Nickname: The Horsemen|
"There are no easy games at this stage," warned the Israel international.
"We're not 100% yet because it's the beginning of the season but we have another match on Saturday [a friendly with Rennes] to prepare.
"We know the importance of the Champions League, everyone at the club wants to get there.
"They are unbelievable moments, especially at Celtic Park."
If Celtic prevail against Qarabag, they will reach the play-off round which they must win to reach the group stage of Europe's premier contest.