The Warmdown: City come from behind to beat Porto in Group C
(Photo by Laurence Griffiths/Getty Images)

Manchester City got their quest for a first Champions League trophy off to a perfect start last night, coming out 3-1 victors over the group's top seed, FC Porto. 

Here are our takeaways from the opening night in Group C.

An early scare

Despite entering the game as major underdogs, it was FC Porto who opened the scoring when young Columbian winger Luiz Diaz struck into the bottom right-hand corner of Ederson's goal.

It was poor defending from the home side that led to the goal, Rueben Dias lost possession on the halfway line and it was the goalscorer who took the ball in his stride and broke at City's defence.

Diaz still has a lot to do but took his goal very well, running through the Blues defence skipping past players like they weren't there then striking with a killer blow. 

Penalty controversy

It took only seven minutes for the home side to come up with a reply when frontman Sergio Aguero placed home calmly from the penalty spot.

VAR took three minutes to review the penalty with a nasty looking challenge from midfielder Ilkay Gundogan on Porto goalkeeper Agustin Marchesin being the reason for the delay but no wrongdoing was identified and the penalty was given.  

The clinical Aguero was on hand to fire home - his first Etihad goal since January - and bring the host's level.

All action

It was definitely one for the neutrals last night, with three yellow cards being dealt to City in the first 35 minutes and a constant battle on the touchline between both managers.

There is no historic rivalries between the two although Guardiola once scored the winning penalty for Brescia against Conceicao's Inter Milan back in 2002.

With Pepe being Pepe in the first half clattering Raheem Sterling for the penalty and a flurry of booking throughout it clearly made the two touchline bosses clash on a few occasions. 

Superb substitutes

When you hear the name Pep Guardiola he instantly comes to mind as one of the best managers around but it's not just the trophies that get him that reputation.

His exceptional game management is one of the key traits to the Spaniard's managerial prowess, and that is precisely what was on show last night. 

Ferran Torres and Phil Foden both made their way onto the pitch shortly after Gundogan's free-kick had put the host's in the lead for the first time on the night, and it was the two youngsters who combined for that crucial third goal.

Pep Guardiola has been an outspoken advocate for the five substitutions that UEFA decided to employ in this seasons competition.

And, with a squad bursting with talent, you feel as though Manchester City may see plenty more success from the bench as the competition continues.

Another Injury blow:

With City already in a whole lot of bother injury-wise, especially in the defensive area it was a heart in mouth situation for Pep when he saw Fernandinho go down in added time.

The Brazilian midfielder had only been on five minutes when he went down off the ball causing a stoppage in play, with outcast John Stones brought on in an unfamiliar role to replace the veteran midfielder.

With Nathan Ake, Benjamin Mendy and Aymeric Laporte all injured defenders this could be a chance for John Stones to take his opportunity to break back into the starting lineup. 

Early signs indicate that Fernandinho will miss between 4-6 weeks of action with the injury.