Egan-Riley, City’s Elite Development Squad captain, started under the Etihad lights while Premier League 2’s leading scorer McAtee was introduced as a half-time substitute against the Portuguese champions.
Luke Mbete also entered the fray late on for his senior Champions League bow and although City were frustrated by the visitors, a comprehensive 5-0 first leg victory had already all but guaranteed our progression to the quarter-finals.
And Guardiola was proud of the young trio’s performances, believing their exposure to Europe’s elite competition will prove invaluable as they continue to develop.
Focusing on Egan-Riley and McAtee in particular, the City boss reflected: “CJ doesn’t make mistakes which is so important as a defender (and) McAtee played well.
“Macca is quite calm and a guy who is in a good direction. He got minutes in the second half and has played previous games. He knows the rhythm.
“He has the quality but has to understand the position a bit better. He was confused in the pressing, but he was good.
“45 minutes in the UEFA Champions League is important (for his development).”
City join the likes of Bayern Munich, Liverpool and Real Madrid in the quarter-finals, with the remaining Last 16 fixtures decided next week.
Unlike the first knockout round, Guardiola’s men can now draw other English sides, meaning we could face one of Liverpool, Chelsea or Manchester United depending on their progression into the last eight.
Asked whether he would prefer to avoid drawing a fellow Premier League side, the City boss pointed out that facing difficult opponents is part and parcel of the Champions League’s latter stages.
He said: "I would say no (in wanting to avoid Premier League sides). It is difficult for us but for them too and for opposition from other countries.
“We are in the eight best teams in Europe and we will prepare well.
“Next Friday we'll see the draw and prepare. It's an honour to be there.
“Important teams are already out. We’ll see what happens but already the four [English] teams (could be) in the last eight.”