Just 24 hours after one of the fiercest electrical storms Manchester has ever seen, Sergio Aguero produced a power surge of his own.
Here is a break-down of how the game panned out...
City, as has become the norm under Pep Guardiola, were at it straight from the word go and soon had Monchengladbach on the ropes.
The Blues took just nine minutes to take the lead after controlling the play up that point with incisive passing from back to front and the opening goal came when Aleksandar Kolarov drilled in a low cross from the left and who else but Sergio Aguero was first to the ball, beating Yann Sommer from close range - his seventh goal of the season in only his fifth appearance.
The lead should have been doubled three minutes later when Fernandinho's threaded pass set Kevin De Bruyne clear. The Belgian picked out Aguero who in turn moved the ball on to Gundogan whose low shot was saved by Sommer - a tad more power and the German midfielder would have been celebrating a debut goal.
City were in complete control and with 20 minutes on the clock, Raheem Sterling had missed a good chance and loud appeals for a penalty had been waved away by the referee after Aguero had been wrestled to the ground by Tobias Strobl.
If there had been any doubt about that decision, there was no doubt about the challenge on Gundogan inside the box on 28 minutes that did result in a spot-kick - comfortably dispatched by Aguero to make it 2-0.
The visitors rarely threatened Claudio Bravo's goal and then he was finally called into action on 41 minutes, the Chilean saved low to his left from Lars Stindl's stinging shot from 18 yards.
City were denied a third just after the break when Sterling pounced on a Sommer fumble before teeing up Aguero who saw his shot saved on the line just as he seemed certain to complete his hat-trick.
The Blues were quicker, more inventive and clinical with solid performances all over the pitch. John Stones and Nicolas Otamendi rarely put a foot wrong throughout the game and their partnership continues to blossom.
Sterling came close to scoring on 73 minutes after De Bruyne had put him clear but his attempted nutmeg on Sommer clipped the keeper's shin and went wide of the post.
But the next goal was scored by the man who can't stop scoring - Aguero - as he raced into the box, coolly rounded Sommer and rolled the ball into the empty net for the eighth hat-trick of his City career.
Gundogan, Sterling and Kun all received standing ovations as they were substituted - Gundogan in particular enjoyed a sparking debut - but it was Kelechi Iheanacho who had the last word. finishing with aplomb after good work by Leroy Sane to claim his first Champions League goal and round off yet another superb performance by Guardiola's side.
What it means
City join Barcelona on three points at the top of Group C , though the Catalan side are in pole position after their 7-0 thrashing of Celtic. The Blues travel to Parkhead to face Celtic in a fortnight's time while Barca play away to Borussia Monchengladbach.
City were 1-0 up and cruising when a rare Monchengladbach attack fell to Raffael who teed up a fierce drive only for Stones to throw his body in the way to block the shot - it was brave and showed why the youngster is considered such a promising talent - his reading of the game is second-to-none.
Photo of the Match
GOAL MACHINE: Kun can't stop scoring
Man of the Match: Sergio Aguero
How could he not be voted the best player on the pitch after scoring yet another Champions League hat-trick? As ever the Argentine striker was lethal in and around the box with his first instinctive, his second cool and calm and his third down to skill and natural ability. If he carries on like this expect a record amount of goals for Kun this season who continues to write new chapters in the Club's history books.
Stats and Milestones
Pep Guardiola has now faced Borussia Monchengladbach seven times in the past three years, winning three, drawing two and losing two.
Sergio Aguero has now moved ahead of Francis Lee in the Club's all-time goal-scorers' list.
City continue to improve on the best ever start to a season with a seventh straight victory under Guardiola.
Aguero has now scored eight City hat-tricks.
This was the first time City have won the opening Champions League group stage home game.