The Greek striker believes the Scottish league leaders were anxious against Benfica due to being just a point away from qualification for the Champions League knockout stages
The Bhoys could have qualified for the knockout stages by earning a point at Estadio da Luz but now face an anxious final group game at home against Spartak Moscow.
And the Greek forward admitted after the match that this anxiety had affected his team-mates.
He told Sky Sports: “For the full 90 minutes we were a bit nervous, and it affected our play.
“I don’t think we played very well today. Again the game was really close, I think we lost it in details.
“The best thing we can take away from this game is our hard work and our focus must shift onto the next game. We have to take positives, as we still have a chance to go through.
“We’re just now looking forward to the next game and try to win the game against Spartak Moscow.”
Samaras also stated that the loss of Victor Wanyama to suspension for the clash with Spartak will not be an issue, as Celtic have other players who can cover him in the centre of the midfield.
He added: “Victor is a great player, he is superb in the midfield with his strength and he balances the whole team.
“However, we have enough players in the squad to cover him for the next game.”