Borna Coric feels he is not playing his best tennis, and yet the Croat is still winning. For those with their eyes on the World No. 13, that’s a scary thought.

“In Dubai I was playing in the semi-finals so I was happy with that,” Coric told ATPTour.com. “But I was getting through the matches very, very tough. I won all three matches 7-6 in the third and then I lost [at the BNP Paribas Open] in Indian Wells to Karlovic, which obviously you never know what’s going to happen. Now here, I’ve won the past two matches, so it hasn’t been that bad. I just thought my level of tennis was not there, not what I expected. But that’s normal, it happens and it’s important that I keep competing.”

Perhaps, it’s that attitude that has helped make the Croatian’s past year arguably his best yet. Entering 2018, Coric had made just two ATP Masters 1000 quarter-finals, and he had not advanced past the last eight. But he made three quarter-finals at the elite level last year, including a trip to the Shanghai final and the Indian Wells semi-finals.

“That’s part of the journey. I was stuck between 40 and 50 [or so in the ATP Rankings] for two to three years. I needed to change something to come to the Top 15 and hopefully one day to the Top 10,” Coric said. “There’s a journey. You’re going to have ups and downs and it’s just important that when you’re kind of down, just continue working, focus on the right things, which I think I do. It’s just a matter of time, and the tennis is going to come.”

Coric’s talent has long been clear. He defeated both Rafael Nadal and Andy Murray in 2014 at just 17. But last season was his breakthrough, including a triumph at the Gerry Weber Open in Halle, where he beat Alexander Zverev in the first round and Roger Federer in the final. Kristjan Schneider, Coric’s coach, chalks it up to altering his tactics on the court.

“First of all I think he is much more aggressive and that gives him a chance to make more pressure, especially on the top players because if you play too defensive, you really don’t have a chance against top players,” Schneider told ATP Tennis Radio last October. “He’s working on many things and he’s really a good guy in terms of training because he’s the one to push us to work on the things, and he wants to be better.”

Listen To ATP Tennis Radio’s Interview With Schneider:

Coric did have a slight hiccup after his 2018 campaign. With a short off-season of two weeks to work with, Coric got sick, meaning he got less than a full week of training in ahead of 2019.

“Last year I was really playing great and I was moving up through the year,” Coric said. “It was a really, really long year for me. [My short off-season] was one of the reasons I am not playing great, so hopefully on clay I can play better tennis.”

But Coric is not done on the hard courts yet, battling through two three-setters to reach the fourth round at the Miami Open presented by Itau. And judging by his level against Frenchman Jeremy Chardy in the third round, the 22-year-old feels that he is beginning to turn a corner.

“I think it was a very good match from my side,” said Coric. “I was playing very well — actually, for the first time in the past two, three tournaments since Australia — and I was really happy. That was just a little frustrating, because I lost the first set and I thought I was playing good. So I needed to get back my momentum in the second set, which I did. And then in the third, obviously, I played those important points very brave.”

Coric has an opportunity to reach another ATP Masters 1000 quarter-final when he faces Acapulco champion Nick Kyrgios on Tuesday at the Hard Rock Stadium in Miami. While the Aussie leads their FedEx ATP Head2Head rivalry, just one of those matches has come since 2016.

“[He’s an] unbelievable competitor, one of the best players in the world at the moment,” Kyrgios said of Coric. “Knows how to win matches, is an unbelievable athlete. I’ve played him a lot, so I know he’s not going to give me a single point for free. He moves incredibly well and has an unbelievable backhand.”