The Reds secured a 1-0 win against the Jets at Marden Sports Complex on Wednesday night.
A thumping header from Michael Marrone on 63 minutes, off Johan Absalonsen’s well-whipped corner, guaranteed Adelaide’s progression to the next stage of the tournament.
United will now host bitter rivals Melbourne Victory in the Round of 16 later this month.
Kurz said it was great to get his maiden win with the Club and stated the mood in the dressing room is high following the hard-fought triumph.
“The feeling is good,” he said. “I think we had a good game Wednesday, we worked hard and the feeling in the team and by the coaches are good.”
Kurz admitted his side had to work tirelessly for the victory, but was pleased the team overcame a very experienced Newcastle outfit.
“I think we had to work hard in the game,” he said.
“Newcastle is a very experienced team with a great offensive style that they played against us.
“But we performed well and I think the attitude from the players are great and that’s what we saw in the game.”
When quizzed about the outings of debutants George Blackwood and Absalonsen, the German boss said he was impressed with not just them but every player’s performance.
“I think the same like the other players,” he said.
“All the players played well in the win and the teamwork was the biggest point which was important in winning the game.”
Kurz also discussed the fitness of Senegalese star striker Baba Diawara, who made a brief cameo appearance off the bench in the dying stages of the match.
“We must see over the next few weeks,” he said.
“Baba (Diawara) has been training two weeks with the team and he didn’t have the fitness levels compared to the rest of the squad to start on Wednesday.
“But I think in the next two weeks he can be a starter."