Bellingham opened the scoring for Borussia Dortmund in their Champions League quarter-final second leg on Wednesday night against City.
It wasn’t enough to prevent Guardiola’s men from progressing, as goals from Riyad Mahrez and Phil Foden sealed a 2-1 win for City and a 4-2 triumph on aggregate.
The future of English football looks bright, with Bellingham producing another masterful performance in midfield that belied his tender years, while Foden continues to be the player for big occasions for City.
Asked about former Birmingham City star Bellingham, Guardiola said: “I cannot believe it, maybe he's a liar! He's so good for 17-years-old, he's a fantastic player.
"There was one moment when he didn't get the ball from central defenders, how he shouts and demands that ball to him at 17 means a lot.
"I spoke with his manager, Edin [Terzic], and he told me what you see in these two games is like every training session."
While Bellingham isn’t completely assured a place in Gareth Southgate’s squad for Euro 2020, it would now be a major shock if the teenager was left out after his stellar performances in both legs of the Champions League tie.
Foden, however, is a shoe-in for a place in the 23-man squad, and is showing every week why he should also be in Southgate’s starting XI.
His fierce left-footed shot sealed the tie, after he also scored in the first leg, and Guardiola had nothing but praise for the 20-year-old.
“He scored two important goals to help us be in the semi-finals," the Spaniard said. "He is learning to make decisions.
"He always creates something. He is dynamic offensively, defensively and in the small spaces.
"You have the feeling he is a guy who never hides."
While City progressed, goal-shy Liverpool were knocked out by Real Madrid 2-0 on aggregate after a goalless draw at Anfield. It means Real will go on to play Chelsea in the last four, with City taking on Paris St Germain.