Chelsea are set to sign Senegal defender Kalidou Koulibaly from Napoli on a four-year deal.

The 31-year-old flew to London on Wednesday to undergo a medical and finalise the move, before he joins Chelsea on their United States tour.

Chelsea are also close to bringing in Manchester City centre-back Nathan Ake.

The pair would bridge the gap left by this summer’s departures of Antonio Rudiger and Andreas Christensen to Real Madrid and Barcelona, respectively.

Earlier on Wednesday, Chelsea confirmed the signing of England forward Raheem Sterling from Manchester City in a £50m deal.

Koulibaly, who has attracted interest from several Premier League clubs, joined Napoli from Genk in 2014 and has made 317 appearances for the Italian top-flight side.

Chelsea are training at the University of California, Los Angeles (UCLA), and Koulibaly will join the squad in either LA or Las Vegas.

Sterling could be available to play in the Blues’ opening tour match in Las Vegas on Saturday against Club America.

Thomas Tuchel’s men then face Charlotte FC in Charlotte on Wednesday, 20 July before taking on Arsenal in Orlando on 23 July.