A brace from Liam Delap and a fantastic solo effort from defender Jair Cunha saw Nottingham Forest past Enzo Maresca’s Man City.
Forest have now moved out of the relegation zone and up to 16th with nine points from their 10 Premier League games so far this season.
As for Man City, this loss is their third consecutive defeat in the Premier League, but they remain in second, six points off Arsenal at the top.
Speaking to BBC Match of the Day after the game, a clearly delighted Glasner hailed his side’s 'amazing goals and great team effort'.
"You can never plan to win 3-1 against City because are so good,” he said.
"But today, especially the players and our fans deserve this win because they were so passionate from the first minute, scoring nice goals.
"We had moments to suffer but then we could rely on our fans pushing us, supporting us. Amazing goals and such a great team effort today so really proud.
"I think we've had better performances in possession because today we rarely had the ball. Regarding the team spirit, the energy, I think it was our best game.
"The way we play football I think we've had many better games but how we defended, how passionately we defended, how tactically smart we defended, it was one of our better games."
On outrunning City: "I think it is the only way you can beat Man City. They're so good, such great players, such a good structure and they move the ball so quickly.
“They can play through the middle, they have incredible dribblers on the wing and they have such pace. Then, of course, they have Haaland in the middle.
"You should control everything and if you want to control it, you have to run because you have to be so quickly aware.
"Of, course you can just defend but you also need to go forward and this is what we did today in the right moments, we scored the goals in the right moments and credit again to the players."
On Liam Delap: "When you come in with a price tag on your back everybody believes 'if you pay so much, he has to score all the goals'.
"I would say it's Liam's second regular Premier League season because he didn't play a lot at Chelsea. He had one great season at Ipswich then lost a lot of confidence at Chelsea, so now he's getting better and better into rhythm.
"These goals are his biggest strengths with his right and his left, also using his power and his strength. We knew that he would score goals for us and today, they were nice ones."