The Frenchman has struggled with injury problems at the Stamford Bridge club over the past few seasons.
But he put a shift in against FC Porto in the second leg of their Champions League quarter final, playing 90 minutes and helping the team progress into the semi finals.
Tuchel said post-game: "We took the risk because we know that maybe this was the moment. Maybe it was not a risk, but the situation and put him on the field and hope he had the energy for 90 minutes.
"N'Golo is incredible, he is like one and a half or two players. Everybody who sees him for the first time loves him, all my family love him when they watch our games now. It's so nice to have him.
"He wins so many balls, he gives everybody confidence and at the same time, like I said, we also did it for Kova.
"We were not sure if N'Golo would start today if we had everybody available but also, it was perfect. Now it is time to recover."