The 22-year-old Norwegian had been kept remarkably quiet, but only needed the slightest glimpse of goal to extend his scoring streak to six games as his telescopic left leg prodded home the winner six minutes from time.
Haaland has now scored 13 goals in nine games for City since they met his bargain 60 million euro ($60m, £52m) buyout clause from the German giants.
"Everyone knows how important a person Johan Cruyff was in my life. As a person, educator, mentor, everything," said Guardiola. "He scored in Camp Nou an incredible goal against Atletico Madrid (in 1973) that was quite similar. The moment he (Haaland) scored, I thought of Cruyff."
Haaland's incredible flexibility despite his giant frame also drew comparisons from Guardiola to another former Barcelona striker Zlatan Ibrahimovic.
Ibrahimovic endured one unhappy season under Guardiola at the Camp Nou, but has used an upbringing in martial arts to devastating effect during his long and storied career.
"I remember my dear friend Ibrahimovic had this ability to put his leg on the roof," added Guardiola.
"Erling is quite similar. He's elastic, flexible and after has the ability to put it in the net. He's so big, but has this natural flexibility."
"In the end we showed what we are. This is how we have to play. I'm proud of the last 20, 25 minutes," said Haaland.
"Two wonderful goals today – mine was a bit better, honestly! It was a nice cross from Cancelo and in the end a really important win."
Victory sees City open up a three-point lead at the top of Group G, with Dortmund still in second after FC Copenhagen and Sevilla played out a 0-0 draw in the Danish capital.
