Griezmann spoke to Barça TV about his - and the team's - plans during their stay in Lisbon.
He said, "We are looking forward to it, we have worked well tactically and we are ready to play the game. We know it will be difficult, but we know what we have to do to qualify for the semifinals. It will be a very good match.
"On a physical level it's tiring due to the heat and the accumulation of matches, but the strangest thing is to play without our fans and their support." We see their messages on social media and this helps us through difficult times."
Griezmann added: "It feels more like an international tournament with the national team. It's different, but it's good to be able to spend time with team-mates, talk about football, talk about life and enjoy working together to win. We have three games left to win the Champions League. We will have to all be together in the good times and bad."