The Spanish outfit were defeated 2-1 in the first leg, but the Frenchman has insisted that they can still advance to the last eight.
"We lost at home but nevertheless we have chances to win in Paris. In football, nothing is impossible," Cissoko told reporters at a press conference.
"It will be a tough match; we will have to be patient. I'll have to be strong in defence."
Cissokho is expected to start at left-back for the European tie.