Madrid, Jul 1 (IANS): Former Spain international Iker Casillas has returned to training with Porto just two months after suffering a heart attack which many believed would end the illustrious career of the ex-Real Madrid goalkeeper.

Casillas reported back for the first day of training with the Portuguese club and confirmed the news with a tweet that said, "Back to work: First day," Xinhua news reported.

His rapid return is surprising given that he had to be rushed to a hospital after suffering a heart attack during a training session with Porto on May 1.

He was discharged from the hospital five days later after undergoing catheterization, but there were still major doubts whether the 38-year-old, who represented Spain in 167 matches, would play again.

Casillas even had to deny reports in May that he was going to retire and had not confirmed when he would return to action until Monday.

He joined Porto in 2015 after spending his entire career with Real Madrid, winning five La Liga titles and the Champions League on three occasions.

In 2010, he had led Spain to World Cup glory.