Karanka was attending matters pitch-side because of Madrid coach Jose Mourinho being at the stands following his touchline ban, and was pleased with the players’ display in Zagreb.
"Those who thought it would be an easy game were wrong," the Spaniard is quoted as saying by Madrid's official website. "Dinamo were very motivated tonight [Wednesday].
"There are surprises in every venue and it's never easy to win. We took three points from a complicated venue. They have a great crowd that boosted their confidence."
Karanka also expressed his optimism for more positive results as the season progresses and enthused: "We must keep this up, growing and working hard to do a good job.
“It's easier to work when you earn positive results. If we keep this up we'll reap rewards.
“We've been thinking solely on ourselves since the pre-season. Things are better each day and we should reap rewards if we carry on this way.”
The other Group D game on Wednesday was between Ajax and Olympique Lyonnais in Amsterdam and it ended in a goalless draw.