Jose Mourinho's side were paired with the Russians in the round of 16 of Europe's elite tournament, and the 30-year-old goalkeeper warned that a difficult tie lies aheadReal Madrid captain Iker Casillas has admitted that his team's opponents in the first knockout round of the Champions League CSKA Moscow are a team to be reckoned with.
Jose Mourinho's side were partnered with the Russian outfit in Friday's round of 16 draw in Nyon.
The away leg of the tie is set to be particularly troubling for Real Madrid as the Spanish outfit will be forced to play in poor weather and on artificial surface.
The Spain international goalkeeper echoed the sentiments of Emilio Butragueno in feeling it will be a difficult 180 minutes.
"We know of our second-round opponent in the Champions League, CSKA Moscow," the 30-year-old told Mundo Deportivo.
"I've seen a couple of their games and I think they are a dangerous team; I do not trust them.
"The temperatures and the pitch will be factors to consider," he stated.
With the first leg not until well into the new year, Casillas knows his side must concentrate on matters at home before thinking about their European campaign.
"However, until February there is no time to prepare for the game. Now we have to focus on other competitions; La Liga and the Copa del Rey," he concluded.
Madrid face Sevilla at the Sanchez Pizjuan on Saturday, and can move back top of the Primera Division if they avoid defeat.