The former world number four hit no less than 62 winners over the course of a three-hour, 10-minute match in which Rune broke Zhang in the final game to clinch his ticket for the next round.
“It was an incredibly tough match,” he said after the match. "It got very close at the end. I’m super happy I got through. First win of the season, it’s always a special feeling. Just super happy to be in the second round, hope I can keep it going."
Despite having to battle hard for the win, Rune was surprisingly happy to get a lot of time on the court after having played only one competitive match leading up to the Australian Open.
"I'm actually happy that it was a long match, with a lot of hard-hitting and baseline duels which allowed me to establish a rhythm. In a way, it's better than if I had won in one hour and ten minutes in three sets", he said.
Rune lost the first set of the match, where he also seemed a bit tense. And he also acknowledges that he needed to shake off initial nerves before getting back into his normal stylish stride.
"I was quite nervous, it was a bit hot, and the first round is always just a bit different."
"But I got to play a little over three hours. It felt good and I got the tension out of my body, said the Dane at the press conference after the win.
Overall, he was pleased with his performance in the first-round match at the Margaret Court Arena in Melbourne.
"I think I played good tennis. I served well and returned well. It's not a sprint, it's a marathon when you play games like this. So it also applies not to stress along the way", said Holger Rune.
Rune will face Italian Matteo Berrettini next in the second round.
The match has not yet been scheduled, but is expected to be played on Thursday morning