Haaland along with fellow new signings Sergio Gomez and Manuel Akanji are all in line to face their former club at Etihad Stadium.
The focus may be on the 22-year-old Norwegian who has hit 12 goals in eight games since joining City but Guardiola sees beyond that.
“They know these players better than I know Dortmund players, that’s for sure,” Guardiola told reporters.
“They can get that benefit but well see if its an advantage or disadvantage, but these three know the qualities of the Dortmund players too.”
On Haaland’s form, Guardiola added: “Hes young, hungry, its going to happen, he can improve.
“He’s 22 and can be better. The connection with his mates, over time, will improve and he will be an even better player.”
Sevilla are away to FC Copenhagen in the other group game.
Elsewhere on Wednesday, new Chelsea boss Graham Potter takes charge of the Blues for the first time when they entertain Salzburg at Stamford Bridge. AC Milan host Dinamo Zagreb in the other group game.
“Its a really exciting project and they have really exciting ideas about how to take the club forward so it felt really positive,” Potter said.
“It has been a whirlwind in terms of getting to know people, leaving Brighton, learning about the players and getting to know them but so far its been really positive. My first impressions have been really good and Im really looking forward to starting.”