The Portuguese outfit play host to their Iberian rivals this week with both teams sitting on three points after one match in Group G.
"We know the importance of the home games, and it is very important for us to win our next two matches here in order to have a comfortable margin to face what's left of the group," Fonseca told reporters.
"Each game has difficulties, and this team will pose us problems to solve, problems that we do not have in our championship. I consider Atletico an Italian team in a Spanish championship. They are very deep when they defend, but they are also very balanced.
"We have to be a team which manages all the moments of the game without losing that balance. Also, we need to have lots of patience to find the spaces which are almost non-existent in their defence."
Atletico head into the match on the back of a 1-0 defeat over Real Madrid at the Santiago Bernabeu at the weekend.