CELTIC goalkeeper Joe Hart has paid tribute to his former Manchester City team-mate Sergio Aguero after the Argentinian striker announced his retirement at the age of 33.

The Barcelona player was taken to hospital in October after experiencing 'chest discomfort' during a match and as taken the decision to hang up his boots in order to protect his health.

Aguero - also known as Kun - and Hart played alongside each other in Manchester for five years and when asked if he had a message for his old friend, the shot-stopper was effusive in his praise.

"Kun – sad news mate," Hart told Sky Sports.

"But I think it goes without saying that the entire footballing world appreciates you for the player that you are and everything you’ve achieved in the game, all the smiles you’ve put on people’s faces.

"I’ve been lucky enough to know you from a personal point of view.

"You were a great team-mate and a good friend.

"I wish you good luck in the future.

"It’s sad but also I think it’s important to look at all the amazing things you’ve done and the smiles you’ve put on people’s faces.

"Good luck for the future and congratulations on an amazing career. Stay safe."