Fabian Marozsan, still "the new guy" on tour, after Holger Rune upset: "I can’t believe what just happened!"

MIAMI, Fla.—Fabian Marozsan’s smile still had a hint of disbelief in it nearly an hour after one of the biggest—and most emphatic—victories of his career. The 24-year-old, making his debut at the Miami Open, had just completed a 6-1, 6-1 stunner over No. 6 seed Holger Rune for his third Top 10 victory.

And afterward, his reaction was about the same as everyone else who witnessed the second-round upset on Sunday:

“When I came out of the Stadium I said to my coach, ‘I can’t believe what just happened!’” Marozsan told press. “It was very quick! Just, like, one hour or something like this…

“It’s still a new feeling for me. I’ve never played before in Miami, I’ve never played in the stadium. These are all new things for me, but I was very happy to win so (comfortably) today.”

While he still considers himself a newcomer on the ATP Tour, Marozsan has been looking increasingly comfortable on the game’s big stages. The Hungarian reached the third round in his Australian Open debut, his best Grand Slam result to date, with a victory over No. 22 seed Francisco Cerundolo along the way. He backed it up with a run to the fourth round in Indian Wells, including a 3-6, 7-5, 6-4 victory over No. 24 seed Nicolas Jarry.

WATCH: Fabian Marozsan picks apart Holger Rune in knockout Miami performance | Highlights

In Miami, Marozsan didn’t pull any punches against No. 6 seed Rune as he broke serve five times in the match—twice in the first set and three times in the second—and saved all three break points he faced to reach the third round. He has now advanced to that stage or better at all three ATP Masters 1000 events that he’s played in his career to date.

“I really enjoy playing here at the highest level. I had a great day today, and I enjoyed every moment on the Stadium Court,” Marozsan said. “I played against a very talented player, he’s a Top 10 player who has (all the potential) to be Top 3 one day.

“I tried to put pressure on him and played very, very high-intensity tennis. He didn’t find the way to come back or do something different. But for me, (when I’m playing) I try not to focus on him, I just try to focus on my game.”

Sitting at a career-high ranking of world No. 57, Marozsan is all but guaranteed to break the Top 50 for the first time after Miami, according to the ATP Live Rankings. That means he will have already crossed off his biggest goal for the season, as he now sets his sights on the Top 30.

The Hungarian announced himself to the tennis world nearly a year ago in Rome, where he stunned world No. 2 Carlos Alcaraz on his way to the fourth round, having come out of the qualifying rounds.

In fact, he has now won three out of his last four matches against Top 10 players, having also defeated Casper Ruud last year in Shanghai, where he went on to reach his first ATP Masters 1000 quarterfinal. The result sent him rocketing up the rankings, from No. 91 to 65, and he’s shown no sign of slowing down since.

“That’s a good stat!” he said with a surprised smile. “But I don’t know why I’m special in these matches. I try to do my best on court, and things happen sometimes.

“I see myself as a new guy on the ATP Tour, and I try to enjoy every moment here… I’m very hungry, that’s the key.”

Marozsan will take on Alexei Popyrin in the fourth round on Monday.