Speaking after Senegal's 2-1 win against Poland on Tuesday night, Koulibaly stressed that Sarri would need time at Chelsea but is confident that he will ultimately deliver exciting football. The Chelsea board are more interested in exploring younger attacking options like Anthony Martial of Manchester United and Christian Pulisic of Borussia Dortmund. His decision to leave Napoli at the end of the season after they fell just short in their search for their first Scudetto since 1990 ignited the rumours further.
But the move will be on hold until Chelsea officially announce Sarri as their new manager to replace Antonio Conte.
Sarri's move for Martusciello will see the pair reunite at Stamford Bridge after spending time together at Empoli, prior to Sarri's departure for Napoli's top job in 2015.
Although a deal between Sarri and Chelsea has not been reached, Koulibaly said: "They [Chelsea] can expect nice football because he is a very good coach".
Los Cafeteros look to open World Cup play with a win
Colombia and Japan are in Group H alongside Poland and Senegal . - Japan are on their sixth World Cup appearance, having made their debut at the 1998 tournament in France.
"We have now a big coach and we know we can win something with him".
"I can only speak on behalf of my client and reaffirm that there has not yet been any meeting with the Chelsea management".
The summer transfer window is open and managers are working hard on their transfer targets so we'll bring you all the latest gossip from around the globe.
David Luiz, who was cast aside by Antonio Conte last season but was integral to the team that won the Premier League in 16/17, could also find himself back in the starting lineup due to his ability to play out from the back.