The 18-year-old, who earned a league winner's medal after making five appearances last season, also caught the eye of City's record signing Riyad Mahrez as the champions sauntered to victory and were unlucky not to score more than just Sergio Aguero's brace.
"Phil Foden is ready for the Premier League, he was last season and now he has one more year experience," said Guardiola.
"It's so good for us."
Mahrez, who finally moved to City for £60 million ($78 million) from Leicester having been frustrated in January when the 2016 champions demanded over £80 million, concurred Foden displayed maturity beyond his age.
"For a guy of 18 years it's very good and he is improving every day," said Mahrez, who started the match but went off in the second half.
Guardiola, who unlike his opposite number Maurizio Sarri was able to field several of the players who starred at the World Cup such as English duo Kyle Walker and John Stones, said his side had treated the match, played in boiling hot weather and which featured drinks breaks, in the right spirit.
Even though the game -- contested between last season's champions and the FA Cup winners -- is largely considered a pre-season crowd-pleasing friendly it still has a trophy for the winner.
"It was hard but the players played really well," said Guardiola.
"Our mentality was right and we got the win.
"We prepare game by game. Our results will determine who we are. We will see at the end of the season what our level is."
Mahrez, who shook off a knock to his ankle he sustained last weekend against Bayern Munich, said they carried out Guardiola's instructions to the letter.
"The manager wants us to control the game from start to end and I think we did that well," said Mahrez.
"Its been good (our summer preparations), we've had some good games and we've prepared well for the game today and we were ready.
"It was a competitive game, when there's a trophy you have to win it and now we are going to recover and be ready for the next game (their Premier League opener against Arsenal next weekend)."