The legendary Spanish stopper put an end to his Real Madrid association in 2015 by heading to the Portuguese league with FC Porto.
He’s been unable to replicate his heroics for his latest side with the 36-year-old being dropped for the Champions League fixture against RB Leipzig.
And in a period of uncertainty about his future, it appears a move to the Premier League could be on the cards.
But if rumours are to be believed, Liverpool also face competition from fellow league side Newcastle who are in the hunt for a new stopper.
While Rob Elliot has impressed in goal for Newcastle, Rafa Benitez is hoping to sure up his options with the addition of the Champions League winner.
Casillas may not be the keeper he once was, though he still boasts a wealth of experience following his incredible trophy-haul at the Bernabeu.
From La Liga and Copa del Rey titles to not one but THREE Champions League winners medal.