Kalidou Koulibaly
Kalidou Koulibaly has committed his future to Napoli by agreeing a new contract Francesco Pecoraro/Getty Images

Chelsea's hopes of completing a future deal for Kalidou Koulibaly look to be all but over after confirmation that he has signed a new contract with Napoli. The Senegal centre-back was heavily linked with a move to Stamford Bridge throughout the summer transfer window, but has now agreed an extension that should keep him in Serie A for a further five years.

News of that renewal was first revealed by Napoli president Aurelio De Laurentiis, who tweeted via his official account: "I'm happy to announce that Kalidou Koulibaly has renewed his contract with Napoli until 2021."

New defensive recruits were a clear priority for Antonio Conte during his first transfer window in English football alongside the signings of striker Michy Batshuayi, tireless midfielder N'Golo Kante and third-choice goalkeeper Eduardo, although the club notably struggled in their pursuit of Serie A-based targets.

With a deal for Juventus stalwart Leonardo Bonucci seemingly out of the question, Chelsea tried in vain to negotiate deals for Koulibaly and highly-rated AC Milan youngster Alessio Romagnoli. The former appeared to be of particular interest and De Laurentiis even claimed earlier this month that Napoli, who have strengthened their own backline with the respective additions of Lorenzo Tonelli and Nikola Maksimovic, received a formal offer worth €50m (£43.1m, $55.8m).

Such a bid was not enough to land the 25-year-old, however, and Conte subsequently had to settle with a deadline day return for the erratic David Luiz and the signing of former Sunderland and Bolton Wanderers left-back Marcos Alonso from Fiorentina.

Alonso has yet to make his debut appearance in a Chelsea shirt, although is expected to feature during Tuesday night's (20 September) EFL Cup third-round tie against Leicester City. Luiz, meanwhile, endured a second west London debut to forget last week as his new side fell 2-1 to Liverpool in their first defeat under Conte.

As for Koulibaly, he does not appear to have been adversely affected by that distracting summer transfer saga and has featured in all five of Napoli's 2016/17 matches to date. Maurizio Sarri's men currently sit top of Serie A following last week's 3-1 win over Bologna.

Twitter/@ADeLaurentiis