City extended our perfect start in the Premier League with our fifth win in five matches with a 3-1 victory over West Ham in a game where we had a total of 29 shots.
But the hosts offered plenty of threat and Ederson was called upon in key moments, including making a full-length save to deny a Kurt Zouma header that was arrowing into the bottom corner.
Much of the praise for Ederson often surrounds his brilliant quality with the ball at his feet and his ability to start attacks but Guardiola says he is a big reason why City do not concede many goals.
“He’s matured and he’s getting even better,” Guardiola said ahead of the Champions League opener against Red Star Belgrade on Tuesday.
“We are a team that doesn't concede too much and I have the feeling that when the opponents arrive he is there.
“The first save in the one-on-one against [Michail] Antonio, the moments he makes the last touch a little bit longer he was there.
“Especially the corner, with [James] Ward-Prowse he is an incredible threat, and Zouma with the tall incredible headers but he made a good save and at that moment it was 1-1.
“We had 16/17 shots in the first half against West Ham which is quite impressive, but these details make the difference and Ederson was there again.”
Ederson played a big part in City landing the Champions League for the first time last season, keeping seven clean sheets in the 11 matches that he started.
That included the final against Inter when he made a couple of huge saves in a 1-0 victory on the unforgettable night in Istanbul.
“There are many, many things but of course Eddie was a key point, a really key point.”
City, who will also face Swiss side Young Boys and German opponents RB Leipzig in Group G, start the competition as holders for the first time.
But Guardiola says it does not make any difference in the way we will approach this season’s challenge with the focus on firstly making it successfully through the group stage.
“Every season we start the competition with the first game and always the target is to win the first one, qualify from the group stage, for the last-16 and try to win the Champions League,” he said.
“Nothing changes from before when we didn’t win it or now we won it last season, nothing changes.
“There's no more [priority] than Red Star tomorrow, it depends on our performance and level what happens.
“Of course we are incredibly happy to try to defend this crown but this competition won’t allow you many mistakes.
“The success we had in group stages is because of the success we had at home. never miss one shot except in the first year against Lyon.
“Always we are so strong at home, making nine points from nine and when that happens and win just one game away you qualify. Tomorrow is the first step. And hopefully we can continue, convince the players we are serious, always we've done it, no matter the opponents and we try to get the first three points.”