Brighton came from behind to win 2-1 thanks to goals from a successful James Milner penalty and Brajan Gruda's strike.
Hurzeler said afterwards: “Sometimes football is not so much about tactics but about energy, intensity and togetherness on the pitch and when the substitutes came on they made the difference. As well as what they do they also spread energy to their teammates and the whole crowd got energised too - and that is very important in football.
“When we equalised we had the belief. The players weren’t happy or satisfied with 1-1, we want to go for the second and I think we deserved the win.”
Brighton also defeated Pep Guardiola's City at Falmer stadium last season and Hurzeler added: “Pep is the best coach in the world and it is always a big challenge to face and compete against him. He always had new ideas and you have to adapt.
"But it's not a one man show, it is a team performance. I am very happy that my players delivered that for us on the pitch. They committed to each other, suffered together and at the end got a very important result for us.”