The Blues fell behind in the 44th minute through Raheem Sterling's opener, but they were handed a lifeline just before half time as Sergio Aguero's attempt at a panenka penalty failed to fool Edouard Mendy.
Tuchel's side responded in the second half through Hakim Ziyech before Marcos Alonso snatched a late winner, and that result maintained Chelsea's astonishing unbeaten record on the road under Tuchel.
The German manager has now managed to navigate his first eight away games unbeaten in the English top flight, following in the footsteps of John Gregory, Luiz Felipe Scolari, Chris Wilder and Kenny Dalglish.
In contrast, his adversary Pep Guardiola oversaw Man City's fourth league defeat of the season at the Etihad on Saturday, which represents the worst home record of his managerial career so far.
Chelsea's win delayed Man City's seemingly inevitable coronation as Premier League champions, and the West London outfit rose to third in the table courtesy of their Etihad victory.
Sparta Rotterdam 
Ajax 
Roma 
Parma 
Dundee Utd 
Celtic 
Valencia 
Alaves 
PSV 
Feyenoord 
Bordeaux 
Rennes 
ST Etienne 
Marseille 
Monaco 
Everton 
Chelsea 
Leicester 
Wolverhampton 
Manchester Utd 
Bournemouth 
Real Madrid 
Sevilla 
Cremonese 
Sampdoria 
Tottenham 
Liverpool 
VFL Wolfsburg 
Borussia Dortmund 
Las Palmas 
Espanyol 
Monza 
Juventus 
Lens 
Paris Saint Germain 
Fiorentina 
Udinese 
Benfica 
Estoril 
Inter 
Como 
Manchester City 
Fulham 
Nottingham Forest 
Motherwell 
ST Mirren 
Rangers 
Carrarese 
Arsenal 
Ipswich