The transfer pits one of the best young strikers in the world against Virgil van Dijk, one of the football's best defenders.
The two have met previously, and their duels have included snapped fingers, feats of strength and a lot of mutual respect.
Known for his strength and speed as well as his eye for goal, Haaland managed to score against Van Dijk in a 2019 Champions League group game when the striker was at RB Salzburg.
But, in the second leg, Haaland was shown who was boss when Van Dijk's pace chased him down and outmuscled off the ball.
However, after handling him well a few years back, Van Dijk found out just how good Haaland has become since his move to Dortmund.
The pair faced each other in the 2022 World Cup qualifier between Norway and The Netherlands in September, and the new City star scored against the Liverpool defender.
And it wasn't just a goal that left Haaland lingering on van Dijk's mind. The pair had such a feisty encounter that the striker ended up accidentally dislocating his opponent's finger.
Van Dijk wasn't best pleased, as Haaland recalled. "I do not know how it happened. He just said 'f***ing hell, you broke my finger," he later explained.
Van Dijk spent the rest of the game with his finger wrapped up having been tended to by medical staff.
But despite the sore incident, the centre-back still acknowledges just how impressive Haaland is.
"Haaland is a special striker, because he's so strong," the Liverpool star said. "He's quick, he's got all the attributes to make a defender's life very difficult."
The feeling is certainly mutual for the 21-year-old, too, describing Van Dijk as the toughest defender he's played against.
"You know how tall he is, how strong he is and how fast he is, and also the timing is crazy," Haaland said about him last year.
"I don't think I won one duel against him because he's a physical monster."
City have been without a senior out-and-out striker since the departure of club legend Sergio Aguero last summer, but they have coped well.
Now it is hoped Haaland will bring them up another gear.
Get your popcorn out for this one next season…