The Norwegian striker has been in sensational form this season, scoring a remarkable 22 goals in 15 games across all competitions.
He returns to former club Borussia Dortmund on Tuesday evening for our latest UEFA Champions League clash - with City knowing that a win will seal top spot in Group G.
Match preview | Dortmund v City
Guardiola says he knew how powerful Haaland would be in transitions – but says the No.9's ability to find space against a deep lying defence is more impressive than he could have imagined.
He said: “What has impressed me is that I knew he was a guy for big transitions and over 30 or 40 metres he was unstoppable.
“But I didn’t know how good he moves in small spaces in the box. In the end he has scored a lot of goals because he moves really well.
“He is so intuitive and especially he makes movements I like a lot, as a striker, he goes away from the action to after be close to the ball.
This type of movement is not easy for a striker. He's so smart in the right moments to make these movements.
“Apart from that, his work ethic, he’s one of the first to arrive at the training centre, quite similar to Ruben [Dias], and is one of the last to leave.
“He takes care of his body perfectly. He's well educated in the way he has to live as a professional and I think has the intention to be better.
“Of course, he’s scoring a lot of goals, and we are happy that last season he had a lot of problems here in Dortmund, he could not play regularly.
“This season, thanks to our physios, doctors and so on, he's being treated really well and he can play every three or four days.
“This is so important for us and for him, of course.”
Click on the above video to hear what he had to say...
DOrtmund v City
As with all first team matches, there will be comprehensive coverage on the official Man City app.
Two hours before kick off, our Matchday Centre will begin providing live text updates, gathering together all the latest team news, stats, analysis and quotes.
And then just before the teams are announced, Matchday Live will begin, with former City players joining us in the studio to offer their insight.
They will be back at half-time and full-time, casting their expert eye over events on the pitch.
Highlights will follow on Wednesday night, after all matches in this week's round of Champions League fixtures has been completed.