The result means they have not won in 14 attempts away from home in the group stage, as Oscar Cardozo scored the only goal of the game in the 86th minute.

Gordon Strachan's men are bottom of Group D although Caldwell believes the team can lift themselves for the rematch at Parkhead in a fortnight's time.

He told Sky Sports: "I think we deserved a point - we set our stall out to defend and we did well for long periods. (Goalkeeper) Artur Boruc is fantastic, he makes great saves at big moments. The. defence, midfield and attack all worked hard and it's bitterly disappointing to lose it at the end.

"I think (Benfica) are a good team, but coming to Parkhead is a different game. I'm sure they won't be looking forward to coming to our home ground."

Hoops skipper Stephen McManus added: "It's very disappointing to be honest but we need to pick ourselves up and get ready for the next challenge."

Asked about Celtic's dismal European record away from home, McManus said: "When you play away in the Champions League they're always tough games. We set our stall out and we felt we deserved at least a point.

"We believe in our own ability, we will go into the next game full of confidence."

Strachan was impressed by the effort and work rate of his team and felt Benfica had done well to make the ball do all the work.

"You have to handle these blows. It was terrific heart that the players showed today. In the Champions League that helps and quality passing helps you as well, we chased the ball a lot and we had tired minds at the end.

"We had a couple of chances ourselves and on a lucky night I thought we might get the result. I thought it would be our night but it just shows you it's a very cruel game and you have to deal with it."