The 31-year-old collapsed during Cologne's game with Karlsruhe last Friday and was rushed to hospital after being resuscitated at the Wildparkstadion.

Initial tests did not highlight any irregularities with the Turk's heart and it was even rumoured that he would be back in training by the end of the week, but he has instead been sent to one of Germany's leading heart specialists in Hanover as a further precautionary measure.

On Friday, he sent a message to all the club's fans, thanking them for their support and asking them to allow him time to recover.

"I am doing well, but I need a bit of peace," he said.

"I am looking forward to getting back to Cologne and playing for FC Cologne again."

With the Bild newspaper reporting that Ozat's career could be threatened, the defender added that he was taking a cautious approach, and would not return if it risked his health.

"If I have something wrong with my heart, I will not play again," said the defender.

"My health and my family have priority."

Cologne have said they expect to be without Ozat until at least the end of the year.