On the day, it was a classic smash-and-grab for Tuchel's side. City dominated the first half and Chelsea were fortunate enough to go in at the break just one goal down. A goal from Rahem Sterling should have been added to by a Sergio Aguero penalty, but the Argentine's attempted panenka was easily saved by Mendy.
Chelsea came out in the second half a different side, and Ziyech's goal just after the hour mark was well-deserved. In a frantic final few minutes of the match, Sterling had a serious penalty claim denied by the referee, before Spaniard Marcos Alonso snatched a last-minute winner in injury time to give his side all three points.
The victory moves Chelsea up to third and caps off a remarkable turnaround from Tuchel since taking the reins from Frank Lampard. City, meanwhile, will have to wait another day to be crowned champions, although that could still happen this weekend if Man United slip up at Aston Villa.