Chelsea completed the signing of 31 year old Kalidou Koulibaly from Napoli last week on a four year contract.

Some eyebrows were raised over the length of his contract given the age of the Senegal international.

Chelsea boss Thomas Tuchel has revealed the club believes Kalidou Koulibaly will play at his peak for years to come.

Asked if giving Koulibaly a four year contract means the club think he can play at his peak for years to come, Tuchel said: “That’s what we believe, and that’s what he is here for.

“There were always rumours about him leaving Napoli, and it was always super difficult – and in the end impossible – to get him because he was a key player.

“It’s nice he takes the challenge right now, and we have Thiago Silva, who is even older and super experienced and still at the peak of his game.

“We hope Kalidou can do the same and play for many years for us. He is totally fit and ready for the challenge, and he needs to be because we need him in top shape.”