Manager Antonio Conte has called for Chelsea to invest in a new defender before the close of the summer transfer window.

With Kurt Zouma yet to make his return from a long-term cruciate ligament injury and the likes of Papy Djilobodji, Baba Rahman and Michael Hector having all exited the club over recent weeks, the Italian's rearguard options looked somewhat bare prior to Saturday's (20 August) comeback victory at Watford.

While a backline of Branislav Ivanovic, John Terry, Gary Cahill and Cesar Azpilicueta certainly did not lack experience, only 19-year-old academy graduate Ola Aina was able to provide cover on the substitutes' bench.

Thankfully for Chelsea such a shortfall did not prove detrimental as late goals from forward pair Michy Batshuayi and Diego Costa – the latter of whom was fortunate not to receive a second yellow card for simulation – cancelled out an opening goal from Etienne Capoue, but Conte is clearly eager to reinforce that area of his squad before the midnight deadline on 31 August.

"If you look now at our squad, we have only five defenders – four that started today and an academy player Aina," he told Sky Sports. "Ola is very good – he has great potential – but with any young player, you must work to put them in the first team. Sure, he has a good future.

Antonio Conte
Chelsea manager Antonio Conte is not satisfied with his current defensive options IAN KINGTON/AFP/Getty Images

"If one defender is injured or banned, then we are in trouble, but the club and me we know this and we are talking every day to improve the squad. We know that this market is very difficult. It's crazy. I don't want to buy only to buy. I want to buy the right profile for Chelsea, the right investment for the solution and for the future."

Napoli centre-back Kalidou Koulibaly is thought to be Chelsea's primary defensive target, with The Telegraph reporting last week that a move had been made for the Senegalese international that could involve a record fee of £60m ($78.4m).

Ricardo Rodriguez, Nikola Maksimović, Lamine Koné and Kostas Manolas are among the other players linked with a move to Stamford Bridge, while Leonardo Bonucci was also previously mentioned in connection with a possible reunion with former Juventus boss Conte.