He said: "They are the important team in the group with players such as Nakata, Diouf and Ivan Campo. They're very important rivals."
Ramos remains confident, however, his men will finish in the top three positions and secure qualification.
"With the teams that were in the draw, we knew there wouldn't be any easy games and that's how it is," he added.
"However, Sevilla are not inferior to any of these teams. It's a very complicated group and we will need to get a good start.
"Every game in such a short group is decisive and we will have to qualify as quickly as possible so as we don't get to the last game needing a win."