Giggs said: “We only have ourselves to blame.
“We had a lot of the ball and we had the chances. Celtic hardly got our of their own half in the first half.
“But when you are on top, you have to take your opportunities and we did not do that. Now we have to play Benfica again.
“It won’t be easy, we are aware of that. But maybe one thing in our favour is that we know Benfica have to win, so they will have to come out and attack us.
“But we are at home and we know what we have to do. Hopefully we can.”