Brendan Rodgers' side knew they would be up against it in Saint Petersburg on Thurday night given the pedigree of the opposition, but a 1-0 victory over the Russian side in the first leg at Parkhead did at least give the reigning Scottish champions that they had enough in them to see out the tie and progress to the last sixteen.
So another disappointing in night for Celtic in Europe, but what went wrong?
The Italian said: "We deserved to win".
"We have played very well in some games, shown some great qualities". We shouldn't be conceding that type of goal.
The stadium's roof was closed over which was good news for the players and 50,492 supporters, including several hundred in green and white, in light of the sub-zero temperatures outside. I'm confident and we need to play a good game.
"Our belief has always been there. Apparently the magic of Celtic Park really exists - the team won in Glasgow due to the white-hot atmosphere".
"They will be expected to go through over the two legs, so my mindset hasn't changed".
Writing for Sport Express, Gosha Chernov suggested that the Parkhead atmosphere had played a big part in Celtic's first leg win: "Paradoxically, in St Petersburg, Celtic had twice as much of the ball as the hosts, but there was nearly no urgency".
Zenit have never lost a Europa League home match, winning 16 of their last 17 games underlining the task Celtic face tonight.
And with that in mind, he is looking for his side to be clever in how they might take advantage.
Success in European competitions hasn't exactly been something Scottish clubs have enjoyed in recent years, and with Celtic being at the forefront of that, this doesn't help the country's current image in comparison to some of the other more prominent nations around them. Across the two games, we were much the better in the first game and in this game, if we played with a bit more courage and belief, we could have maybe got a result. You talk about defending forward and we didn't do that well enough, and we conceded poor goals from that. We're too deep and have to press the guy who was shooting.