Christensen has spent the last two seasons on loan at German side Borussia Monchengladbach.
But he’s now back at Chelsea and a part of Antonio Conte’s first-team squad.
The Dane could be set for an extended run in the starting line-up following David Luiz’s red card against Arsenal last weekend.
And Christensen has thanked the Brazilian for helping him settle back into life at Chelsea.
“David always does (help) and he is a good person, he wants the best for everyone and for the team,” he said.
“If he sees something, he will definitely say it, it does not matter who.”
On Chelsea playing a back three, Christiansen added: “When I was younger, my teams always played four at the back and then in the first season in Gladbach, we changed from four to three and played that through almost the whole season.
“I was the middle player, so I know that position.
“It is a little bit different what different managers want from a player who plays there but in general it is the same position.”
And when quizzed on his spell with Gladbach, the Denmark international defender added: "I played almost every game and in the Champions League we had difficult groups with Barcelona, Man City, Juventus, Celtic and Sevilla.
"So there were some tough games and it was hard to get something out of them but we did what we could and I enjoyed that two-year loan spell."
