Celtic manager Brendan Rodgers admitted to feeling mixed emotions after his side reached the group stages of the Champions League with an 8-4 aggregate win over Astana.
The Scottish champions had won the first leg 5-0 but suffered a 4-3 defeat in Kazakhstan, where they scored through Scott Sinclair, Olivier Ntcham and Leigh Griffiths.
Rodgers told BT Sport 2: "It's mixed emotions because we didn't defend well enough and our possession at times wasn't good enough either.
"I said to the players (at half-time) we started the game very well. We wanted to control the tempo but we were too loose in our passing and our positioning, we weren't compact enough when they had the ball. That didn't allow us to press.
"I thought we were going to get through this campaign without the anxiety but that little period (at the start of the second half) they scored two quick goals. We were working on the side to plug gaps.
"I then have to give credit to the players because they were on the ropes for 15-20 minutes, but they regained their composure."
Midfielder Scott Brown admitted Celtic had not lived up to the standards they had set in the first leg.
"The first game at Celtic Park was phenomenal for us, not so much coming over here but we knew we would score goals. It was an exciting game for the neutral but not so much for us.
"If you look at the shots on target it was 19-20 shots on target, it was a game of basketball and it's not like us to be perfectly honest. Usually we are very tight and we were a bit too open today."