Brendan Rodgers has claimed that Celtic should have had "more courage and more belief" in their Europa League last-32 second-leg game at Zenit St Petersburg.
The Hoops travelled to the Krestovsky Stadium for Thursday's meeting with the Russian Premier League giants boasting a 1-0 lead from the first leg at Parkhead.
However, Celtic put in a lacklustre performance as Branislav Ivanovic, Daler Kuzyaev and Aleksandr Kokorin turned the tie round in the hosts' favour, sealing a 3-0 win on the night and 3-1 on aggregate.
"Defensively, we lacked aggression, especially in the first half," Rodgers told BBC Sport after the game. "We didn't defend forward well enough. But, at 2-0 down, we were still in the game and we had to show bravery.
"Second half, we started okay, but we again concede the possession too cheaply. Across two games, we were much better than them in the first game. In this one, if we had showed more courage and more belief, we could have got a result.
"I think there's still an awful lot of work for us to do, but there have been a lot of positives for us in both competitions. Last week was an outstanding performance and you would think that would allow us to come into this game with confidence."
Celtic return to Scottish Premiership action on Sunday against Aberdeen at Pittodrie.
