Porto faces Liverpool in the quarterfinals of the Champions League in what looks like a repeat of the second round meeting between both clubs last season.
The Real Madrid Legend has warned Liverpool that this season clash would be different as the Portuguese Champions have more mettle to their game. Porto are one of the surprise quarterfinalists alongside Ajax in the competition.
The Portuguese side scaled through in the round of 16 by defeating Roma 4-3 on aggregate after Alex Telles scored a penalty in extra time in the return leg.
Buoyed by talisman MousaMarega who has scored in all his games so far in the competition Porto could prove to be difficult opposition for the Reds. According to Casillas, the Reds should be worried about his team as they have quality players that can change the outcome of the clash.
Casillas was speaking after signing a new deal with the Portuguese giant extending his stay at the club until 2020. Widely considered as the greatest goalkeeper in Real Madrid history and one of the all-time greats Casillas has been a key fixture in the Porto side.
After his low key exit from Real Madrid in 2015, the Spanish international has made 149 appearances for Portuguese champions. He was a key member last season as the club won its first league title in five years.
At 38 years this could be his last contract for the club and Porto would be hoping that he produces heroics in the tie against Liverpool.