Celtic manager Brendan Rodgers says that the club can take some positives from their European campaign, despite them only winning two of the eight matches they played after qualifying for the Champions League.
Celtic bow out of the Europa League at the first knockout hurdle, and while the former Liverpool boss will console himself with the prospect of another domestic treble, his side have once again fallen short of making a significant impact on the continent.
Roberto Mancini's Zenit secured their place in Friday's last-16 draw in the 61st minute with Serbian global Ivanović again playing a key role as his low cross was bundled in by Aleksandr Kokorin at the back post.
The tie was then completely turned on its head just before the half-hour mark, Daler Kuzyaev's strike from outside the area somehow swerving through the hands of De Vries and into the net. "We didn't close the space..."
"There is still an very bad lot of work for us to do but, when I take a step back, there have been a lot of positives for us in Europe this season." said Rodgers.
That goal gave the Russians the advantage going into the break with a 2-1 aggregate score - but Celtic knew an away goal could swing the tie back in their favour.
The second goal, we didn't engage quick enough from a throw-in.
The Dons, too, were victims of a setback last time out, in their case a 2-0 loss to Hibernian at Easter Road.
"And at the third goal, we conceded possession too cheaply".
"We were much better than Zenit in the first leg". In this one, if we had showed more courage and more belief, we could have got a result.
There is still an very bad lot of work for us to do but, when I take a step back, there have been a lot of positives for us in Europe this season.
"We deserved to win", said Mancini.
"Dembele was very good and aggressive, Ntcham was good and Brown always is, he is excellent for the team", Rodgers said, as quoted by STV. Celtic's tempo in Glasgow was very hard for us.
Visiting coach Maurizio Sarri named a strong team, and Piotr Zieliński's first-half goal gave Napoli hope.