Enzo Maresca's side were looking to record a fourth straight victory, whilst the Dragons were hoping for an eighth win in succession.
Both teams were in good form
The last time the two teams met six years ago, neither were able to find the net in what was a bruising 0-0 encounter, but given that Porto had scored in their previous 10 matches ahead of this game, and the Cityzens were in fine goalscoring form of their own, there appeared to be little chance that this one would end goalless.
Although there'd been no chances of note from either side in the opening quarter hour of the game, the visitors had enjoyed an incredible 76% collective possession in the early stages.
Rayan Cherki (96% pass completion), Marc Guehi (97.4%) and new signing Ayyoub Bouaddi (98.2%) were absolutely imperious on the night, barely wasting a pass despite constantly coming under intense pressure from the likes of Alberto Costa (12 one-on-ones attempted) and Gabri Veiga (13).
Indeed, the ferocity of the battle in the middle of the park at times was a real feature of a game that you couldn't take your eyes off for a moment.
Costa working overtime for Porto
Antoine Semenyo and Erling Haaland were the first two players in the match to have an attempt at goal, both on target, and the former's five crosses in the opening 30 minutes were at least three more than any other player on the pitch (Phil Foden - 2).
Haaland's influence in the game became more noticeable as the half wore on, the Norwegian having another two shots at goal, and being a major cause as to why Porto keeper, Diogo Costa, had already had to make five saves by the 32nd minute - the first time he'd made that many in a game since facing Barcelona in November 2023.
All of the attacking was coming from City, with Porto unable to muster a shot on or off target in the first half.
Nehuen Perez winning 100% of his tackles for the hosts was one of the reasons why the match remained goalless at the break, with Andre Silva also putting in a shift defensively despite his skill set being required at the opposite end of the pitch.
Haaland on target
Haaland had managed only seven touches in the entire first half, but just one minute and 34 seconds after the break, his eighth brought the first goal of the match, with new signing Enzo Fernandez supplying the floated assist for the Norwegian to aim a downward header into the net via the inside of the post.
Defensively, City were superb, with Alan Varela not having Porto's first shot (off target) until the 56th minute of the game.
Guehi's three interceptions and 100% win rate in tackles made were key to the visitors' solidity, as was Bouaddi's two tackles won from three, and both players' 100% pass accuracy after an hour.
Porto's attacks were sporadic, and even when they did get the odd shot away through William Gomes or Veiga, it was off target.
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No shots on target for Porto
Even a flurry of substitutions from the hosts had little effect on the flow of the game, and while the hosts managed to repel City from extending their lead, thanks to the visitors' 68% possession from the hour mark, there appeared little chance they would relinquish their one-goal advantage.
Late Porto sub, Seko Fofana, had an effort at goal within a minute of his introduction, but like his teammates, he too couldn't find the target, with the hosts not troubling Gianluigi Donnarumma all game.
Whilst a number of Porto players can be pleased with their output more generally, for example, Jakub Kiwior won five of his six one-on-one duels and three of his four aerial duels, and Martim Fernandes completed 94% of his passes, Francesco Farioli will be disappointed that his side never really troubled City in an attacking sense.
Indeed, it was the first time since a fixture against Juventus in February 2017 that Porto hadn't managed a shot on target in a UCL encounter.
Another UCL record awaits...
The only real surprise was that it took until injury time for Haaland to slip home his and City's second of the match, leaving him just one goal away from 60 Champions League goals.
His 59 goals have come in just 59 UCL appearances, and with Lionel Messi currently the quickest to 60 goals (80 appearances), Haaland is on course to smash yet another record in the premier European competition.
There was still time for Fernandez to have a hat-trick of efforts at goal, with City ending the game as they'd started it, in the ascendancy.