The emergence of academy graduate Trevoh Chalobah has not persuaded Tuchel that he does not need another defender.
Romelu Lukaku is Chelsea’s only summer arrival so far, being re-signed in a £97.5m deal from Inter Milan.
Speaking after the Blues’ 2-0 win over Arsenal on Sunday, Tuchel opened up on the possibility of more signings.
He suggested that additions could be possible, insisting that Chelsea do not have the biggest squad in the Premier League.