He said: “I’m really happy. Not because of my goal, but because we won the game. The goal was a bonus – the most important thing was that we got through to the next round and stayed in the Champions League.
“We were all worried when they scored. We didn’t want to start the game like that and concede a goal so early.
“That wasn’t in the game plan, but sometimes you need to deal with this kind of thing. The most important thing is that we recovered and scored four goals.”
The plastic pitch in Iceland did not help Celtic on the night, Bitton being one of the few who looked close to comfortable on the surface.
He said: “The pitch was difficult, but it’s not an excuse for us. They play on the same pitch as we did. Okay, they are used to it, but, as a professional, you have to be ready for this. We are not 100% yet as this is the beginning of the season, but we will get there.
Deila’s men face the dangerous trip to Azerbaijan before they can start thinking about the final hurdle in qualifying for the money-spinning group stages.
“There are no easy games, we have to be prepared and we have to go through to the play-off. We have another game on Saturday against Rennes and we want to keep building.
“It was a justified scoreline at the end as we were the better team and, yes, it gives us more confidence.
“We try to improve every day in training. We have new guys coming in and we try to improve our chemistry,
“But we will do that. We will get better with more training and games together.”