Manchester City came from behind with a goal to start their UEFA Champions League football campaign with a victory in Group C after their 3-1 victory over Porto at Etihad Stadium.
City trailed after 14 minutes from the start after Luis Diaz's solo effort, but Sergio Agüero's penalty kick equalized for the hosts before Ilkay Gundogan and Ferran Torres scored twice in the second half, deciding the victory for the English team.
Pep Guardiola's side, who lost in the quarter-finals last season, struggled to find their smooth performance in the first half but Porto fell back after the break in front of City's competence.
And Porto took the lead when Robin Diaz, a newcomer from Benfica, passed the ball to Colombian winger Luis Diaz by mistake, to penetrate into the area from the left side of City's goal and send a low-pitched shot past Ederson.
Soon Guardiola's team rose up to hit Gundogan at the post, and Porto defender Pepe committed a foul against Raheem Sterling in the area, so the referee awarded a penalty kick that was successfully executed by Aguero.
City was far from form, but advanced in the 65th minute with a superb shot from Gundogan's free kick that placed him above the human wall and out of reach of Porto goalkeeper Agustin Marchesen.
Substitutes Ferran Torres and Phil Foden collaborated to make the score 3-1, when the Spanish player received a pass from the English midfielder before he took advantage of the space and entered the penalty area and hit the right foot in the far corner of the goal.
Brazilian midfielder Fernandinho appeared in the 85th minute, but left the field in injury time, apparently due to a muscle injury.
Porto remained without a win in 21 matches in England, but they managed to equalize three times.