Filipe Luis insists former club Atletico Madrid remain one of the most feared teams in this season's UEFA Champions League.
The full-back was part of the team that claimed a surprise La Liga title last term and reached the final of Europe's elite club competition before losing out to city rivals Real.
The Brazilian has since moved from the Vicente Calderon to Chelsea, along with striker Diego Costa, but rates his old side as strong contenders to lift the trophy ahead of the draw for the last 16 on Monday.
He told Marca: "Nobody wants to face Atletico. They are a solid team that don't let in goals easily.
"They may have lost a lot of players but have kept their form. They would be a very difficult rival.
"I'd rather not come up against Atletico, because it isn't easy to beat them, not even scrape a draw. But if we do, we'll have to be well prepared if we hope to win."
Both Chelsea and Atletico topped their respective groups to progress into the knockout stages.