Manchester City came from behind to beat Porto 3-1 in the Champions League Group C on Wednesday at Etihad Stadium.
City trailed in a solo strike from Luis Diaz in the 14th minute, but a Sergio Aguero penalty put them ahead with a second-half goal from Gundogan and Ferran Torres.
Pep Cardiola’s team, who lost in the quarterfinals last season, struggled to find their fluid in the opening 45 minutes, but as Porto got tired after the break, the quality of the city was adequate.
“If I’m honest, we’re fighting right now,” said German midfielder Gundogan.
“Fernandinho eventually came out. We have players playing at different levels. I’m not 100% because I had a coward, we were not all there at the same time.
“This is the challenge for this season and it will not end for a while,” he added
Porto took the lead when City’s Ruben Diaz, who had recently signed from Benfica, gave the ball away and the Colombian winger Dias was cut from the left, exploding crosswise across the City defense and shooting into the very bottom corner of Ederson’s goal.
After Gundogan attacked the post, Porto defender Pepe Raheem piled on Sterling, and Aguero changed the next penalty in the ensuing fight.
City were far from their best run, but went ahead with a perfect, curling free kick from Kundok in the 65th minute just above the wall and beyond Porto keeper Augustine Marchesin.
Torres and Bill Fotten then combined to make it 3-1, with the Spaniard collecting a return pass from the England midfielder before slipping into space and driving a right-footed shot into the far corner.
The city’s Brazilian midfielder Fernandinho was brought in in the 85th minute to stop what appeared to be a muscle injury.
Porto are unbeaten in 21 games in England, managing three draws in a run.