Chelsea head coach Antonio Conte needs to prepare for when John Terry ends his long-serving spell at the club, according to Mario Melchiot.
Terry, 35, has made more than 500 appearances for Chelsea and Melchiot, who spent five years at Stamford Bridge, believes Conte needs to strengthen the team's defensive line ahead of the forthcoming season.
"Chelsea have enough experience at the back, but you have to think what their next step is," he told Sky Sports News HQ
"We don't know how long John Terry will be able to play for. They gave him one more season and that is because he is one of the best they have."
Kurt Zouma has impressed since signing from Saint Etienne in 2014, but the Frenchman has been ruled out since February due to a knee ligament injury.
Melchiot believes the 22-year-old has an important role to play at the club in the future, but says Chelsea need more defenders of the same quality.
"Zouma got injured and played a lot of games. He proved he can hold his own in the defensive line," he added.
"I can see him playing as a sitting midfielder. But he's just come out of injury and is young, strong, talented and dynamic.
"I like him as a player but they need more players in defence. Competition makes players better, and at this point I don't think they have enough."
According to Sky in Italy, Chelsea bid £38m for centre-back Kalidou Koulibaly from Napoli in July in order to add to their defensive options, while full-back Baba Rahman has joined Schalke on a season-long loan.