Chelsea are set to make a club record bid of £60m ($79m) for Napoli defender Kalidou Koulibaly in a bid to bring him to Stamford Bridge as new manager Antonio Conte looks to strengthen his squad. The Blues have been heavily linked with a move for the defender but have thus far failed to agree a fee with the Italian club for a transfer.

The Telegraph reports that Chelsea are unlikely to stop their spending with Koulibaly and are likely to make an improved bid for Everton striker Romelu Lukaku as they want another prolific striker up front despite signing Michy Batshuayi this summer. Diego Costa, who scored against West Ham, is also set to stay beyond the end of the summer.

Chelsea's acquisition of N'Golo Kante has already made them stronger in midfield and should they manage to strengthen at the back and up front, it will prove to be a brilliant summer for the former Italy national team manager. However, Koulibaly's arrival will put into question the future of English duo John Terry and Gary Cahill, who have been the mainstay of the Blues' defence for the last few years.

Conte can also move into a back three, a system he has successfully used with Juventus and Italy. Meanwhile, Kurt Zouma is also recovering from injury and should be back before the end of the year. Conte is unlikely to play Terry and Cahill regularly at the back given their age, which should allow ample game time for everyone if Koulibaly is brought in as the club's fourth recognised centre-back.

Napoli's French defender Kalidou Koulibaly (R) fights for the ball with Frosinone's forward from Italy Daniel Ciofani during the Italian Serie A football match SSC Napoli vs Frosinone Calcio on May 14, 2016 at the San Paolo stadium in Naples Getty

Should he sign for the reported fee, he will become the most expensive defender in the world, ahead of Manchester City's acquisition of John Stones from Everton. The Blues started their premier League campaign in style, with Costa scoring the winner against the Hammers in the final minute of normal time.