The Denmark international has worked his way into the starting line up under Tuchel and is now one of the first names on the team sheet.
There is currently a contract stand-off between Christensen and the club, with the 24-year-old's contract due to expire next summer, but Tuchel hopes he stays at Stamford Bridge for years to come.
"He's a calm guy, very intelligent player, and sometimes you can get maybe a bit misled by judging him from his personality, because he is a hard defender and he is a guy who is not shy to have hard tackles and win challenges and step up in games," said the German coach.
"He found his place. He is very strong, very reliable and he has not reached his limits because at his age there is still room to improve.
"He can be a top defender for us in the next years and hopefully he will be because he comes from the academy.
"He knows what it takes and he has improved massively so far but it is not done yet – you have to show it over and over. There are big examples in this club of what it takes to be a legend in defence and there is still a way to go but we are very happy so far."
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