Chelsea are hoping to complete the signing of one of their main defensive targets by the end of this week.
The Blues are in negotiations for Juventus stopper Matthijs de Ligt and Manchester City ace Nathan Ake.
Thomas Tuchel wants one new centre-back in his squad prior to flying out to America on Saturday for their preseason tour, according to the Evening Standard.
Antonio Rudiger and Andreas Christensen both departed Stamford Bridge on free transfers this summer.
De Ligt is also being targeted by Bayern Munich, however the Germans do not want to be drawn into a bidding war.
The Dutchman does not want to sign an extension with Juventus, with his current contract expiring in 2024.
In the case of Ake, City want to recoup the £41m they spent on the 27-year-old back in 2020.