Tuchel announced on Sunday that Antonio Rudiger will be leaving the club at the end of the season when his contract expires.
Chelsea are also set to lose Andreas Christensen, who has reportedly agreed a move to Barcelona as a free agent this summer.
The Champions League holders also face the prospect of losing captain Cesar Azpilicueta, whose contract also runs out at the end of the campaign.
According to The Telegraph, Tuchel wants Chelsea to bring in two new defenders to compensate for the departures of Rudiger and Christensen.
Sevilla’s Jules Kounde, who came close to joining Chelsea last summer before the Spanish club raised their asking price in the closing stages of the transfer window, remains on Tuchel’s shortlist.
Villarreal’s Pau Torres has also been identified by Chelsea as a player who could provide a solution to the left side of Tuchel’s three-man defence, although Manchester United are also keen on the Spain international.
According to Sky Germany, Tuchel is also an admirer of RB Leipzig centre-back Josko Gvardiol.
The 20-year-old Croatian defender is reportedly viewed by Tuchel as Rudiger’s potential replacement at Stamford Bridge.
Chelsea, however, have been forced to put their transfer plans on hold following the club’s sanctions due to Roman Abramovich’s ownership.
Tuchel also claimed over the weekend that Chelsea’s sanctions played a role in their failure to reach an agreement with Rudiger.
‘We fought hard,’ said Tuchel.
‘I fought hard on a personal level. We made big offers to him, and the club tried everything.
‘But for some weeks we cannot fight any more because we have the sanctions. We cannot adjust. We cannot continue, and so it is what it is.
‘He deserves my full support because he delivered incredible performances right until today.
‘I’m just happy that I had the chance to coach him and to have him in the team. Because he was nothing but brilliant.’
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