The Spaniard is included in the Portuguese side's squad list on the league's official website, so that means that Sergio Conceicao is able to select the goalkeeper to play.
On May 1, Casillas suffered a heart attack during Porto's training session. He was then admitted to hospital, where they conducted a catheterisation. Since that time, the 38-year-old has been recovering.
Casillas joined his Porto teammates for pre-season on July 1, and on July 15 the club confirmed that the goalkeeper would join the coaching team while he continues his recovery process.