Manager Pep Guardiola named a similar starting XI to the one that beat Preston North End earlier in the week, but some familiar faces came back onto the bench.
Four of the front five were youth prospects, while the back half of the team was comprised entirely of experienced first-team players.
Samuel Edozie scored his second goal of the Summer, before goals from Ben Knight and Riyad Mahrez saw Manchester City into a comfortable lead before the break. In the second half it was Nathan Aké who closed the scoring from close range.
Here's what we learned...
Mahrez Gearing Up
One of the big worries Manchester City fans have going into next season is that most of our senior attackers have been on extended holidays after international duty: Gabriel Jesus, Raheem Sterling, Ferran Torres and Phil Foden all reached the latter stages of major tournaments. So did potential signings Jack Grealish and Harry Kane, while Sergio Agüero departed for Barcelona.
So it's been hugely encouraging to see Riyad Mahrez looking nearly at the top of his game so far this pre-season. The Algerian wizard has been leading our youthful attack with some moments of absolute brilliance, and he showed off his immense talent again against Barnsley.
First there was a smart cross to set up the opening goal, then he smashed in a wonderful volley before the break. In games like the Community Shield and the Premier League opener against Leicester, Riyad's sharpness will be a huge help on the attack.
Edozie Impresses Again
Only two players have scored more than once in pre-season for Manchester City so far, and one of them is 18-year-old winger Samuel Edozie. He wasn't one of the names being talked about often ahead of these friendlies- plenty of fans are talking about him now.
It's easy to say that his goal against Barnsley was just a tap-in, but it was exactly the kind of goal that a winger in a Pep Guardiola system needs excel at. The finish was simple enough; Edozie's movement and alertness to get into position as soon as he saw what Mahrez was trying to do made the goal.
If we suffer injury problems out wide this season, it's good to know that we have someone in the academy who can help out and suits the task very well already.
Emphasis on Crossing Returns
The mega-successful City sides of 2017/18 and 18/19 were built on one form of attack above all others: crossing. Specifically, Pep's players focused on low, hard cut-backs from high up the pitch to set up poachers in the middle.
We don't play with physical forwards, so the best way to exploit defenders was to let Sterling, Agüero, Jesus and David Silva ghost into space to tap in at the back post or from near the penalty spot.
Emphasis on that style was reduced slightly over the next two years, but it was back in full force against Barnsley. The majority of City's moves in the first half aimed to get the ball to Cancelo, Mahrez or Mendy on the flanks, who would then drive it back into the path of Knight, Palmer or Edozie.
This created two goals and several other great chances. Whether the re-introduction of this style as the primary strategy is a good thing or not depends on your own tastes- personally, I think playing this way is the best chance we have of getting the most out of our current forwards.
Options in the Academy... If Pep Wants Them
Just a last few words on City's academy: the first two games of this pre-season have, I feel, gone a long way towards changing the perception many City fans have of the EDS.
For all of his brilliance, Pep is sometimes criticised for not making much use of the club's lucrative academy. The usual defence is that the players aren't good enough, and that any who are will get their chance.
I think this game in particular has proven that that notion is shaky at best. Against Barnsley, we saw Edozie, Knight, James Mcatee, Cole Palmer and more youngsters put in highly impressive performances. They've given us no reason to keep assuming that they couldn't perform against senior sides when needed in cup games.
Let's not forget that this is City's first pre-season since Pep took over where youngsters have had to be extensively used as goalscorers, and that's only by necessity. If players like Edozie and Mcatee can get some minutes against Championship sides in the domestic cups next year, there's so many potential top players we could uncover...
Promising Full-Back Displays
Over the first five years of Pep Guardiola's tenure, full-back positions have caused more problems for club executives than maybe anywhere else on the pitch. The list of names that have filled in there is too long to write out and includes Fabian Delph and Fernando, but it's starting to look like we might finally have things figured out.
Benjamin Mendy looks like he's going into the season officially below Oleksandr Zinchenko in the pecking order for (oddly enough) the first time, but on the strength of his pre-season performances he'll make a perfectly good understudy if he stays fit.
Meanwhile, Joao Cancelo is playing well in these friendlies after what must have been a heartbreaking Summer. Both he and Mendy were key components of the team against Barnsley, perhaps indicating that the days of Pep wanting his full-backs to put in crosses are back after a few years of treating them as either wide centre-backs or extra midfielders.
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