Christensen was not included in Tuchel's squad due to illness, but the London club managed without him.
"We missed Andreas Christensen today," said the manager. "Thiago has also been out for many weeks. These are great personalities. I told Kurt Zouma this morning that he was playing and he stepped in. It is about unity, courage and trust with each other.
"It was generally a really good performance, an incredible effort, even from the players sitting in the stands. We could really feel we wanted this.
"They tried to push hard in the first half, but it gave space behind the midfield, and we took advantage of that."