'S-HERTOGENBOSCH, Netherlands -- 2018 champion Aleksandra Krunic earned the fifth Top 10 win of her career after defeating World No.5 Jessica Pegula 7-6(3), 6-7(3), 6-4 in the second round of the Libema Open. 

"It definitely takes a lot to beat Jess on grass," Krunic told WTA Insider. "I think it took absolutely everything out of me today. I don't think I could have done anything better. I was absolutely playing at my 100 percent today."

's-Hertogenbosch: Draws | Schedule | Scores

Now ranked No.400, the 31-year-old Serbian advanced to her first Hologic WTA Tour quarterfinal since 2022 and first on grass since winning her sole title six years ago. She will face Hungary's Dalma Galfi, who stunned No.5 seed Veronika Kudermetova 6-3, 3-6, 7-5 earlier in the day. 

There's just something about Krunic and the grass courts in Holland. She won her only WTA title here in 2018 in a memorable run that saw her knock out top seed CoCo Vandeweghe in the semifinals and Kirsten Flipkens in the final. Later that season, she reached a career-high of No.39 on the PIF WTA Rankings. 

But Krunic came into this year's edition seeking her first tour-level main-draw win since 2022. During her qualifying campaign at 2022 Tallinn, she ruptured her ACL and did not return to competition until Wimbledon last year.

Using her protected ranking this week, Krunic ended her drought in the first round, posting a three-set win over French qualifier Jessika Ponchet. 

Seeded No.1 in 's-Hertogenbosch, Pegula was playing just her second match since April. She returned to action this week after skipping the European clay season to heal a rib injury. 

In their first career meeting, Pegula struggled to consolidate her leads in the first and third sets. She led by a break at 4-2 in the first set, only to see Krunic peg her back and force a tiebreak. There, Krunic's all-court pressure won out, as Pegula lost five straight points to fall a set behind.

"I think my variation was the key and definitely the way I moved," Krunic said. "I knew Jess would be consistent with her powerful shots so I had to be at my highest level of movement. I tried to make her play an extra shot over, and over, and over."

The second set saw a similar pattern but opposite result. Again, Pegula broke serve first and Krunic stormed back. But this time it was the American who won the last five points of the tiebreak to force a decider. 

"I haven't played at this level since my surgeries, so I was worried if I could play the same level in the third set," Krunic said. "But apparently I could."

In the final set, Krunic saved two break points in her opening service game before breaking Pegula for a 2-1 lead. After saving a third break point in the set, she consolidated that lead to 3-1 and did not face a break point for the remainder of the match. 

Krunic spoke to WTA Insider after the match to reflect on her up-and-down career and why she's still plugging away:

Q: You hadn't won a tour-level main-draw match in nearly two years before this week. How important was that first-round win over Ponchet?

Krunic: Competing with someone in the main draw and winning was very important to me mentally, so that I could think I could do this at this level. Now, beating a Top 5 player on one of her best surfaces, it's big for me. It tells me that I can still play at that level and I can compete for three sets at this level.

I have to train harder so I can do this consistently, because I think Jess can do this every match. I think I need a vacation after this (laughs). So I need to get to the point where I can do this in 50 percent of my matches. I'm getting there.

Q: You were pretty down after losing in the first round of Roland Garros. It's funny how quickly your fortunes can change.

Krunic: This surface suits me better, especially since it's better for my knee. Clay is tough for me and challenging still. It's high bounces, it's physical, I don't have enough grip to move. Paris was tough with the balls, conditions, the rain and everything. So for me, at the moment, playing on clay is mentally very draining and tough.

So I think Paris was just so hectic for me. It was just a lot, so I was mentally drained. I'm still tired, but because it's grass and because I feel better with my body, I feel better overall, because feeling good with your body, especially now after everything I've been through, gives me confidence.

It's tennis, every week it can turn. I'm still tired but at least it's good tired. At least I'm tired from Jess making me work my butt off. I will take that "tired". 

From the splits to a steal: Krunic denies Pegula with hot shot

Q: It's been 10 years since that incredible run to the US Open Round of 16 in 2014. When you look back, how do you see your career so far? 

Krunic: I think my career lacked discipline because ever since I was young, I was talented. I always heard "She should be here, she should do that". So success for me, instead of being happy about it, I thought this is what I'm supposed to do. But when I was losing, it was a complete disaster. 

My career was up and down because I lacked the right people to guide me, to tell me you are talented and skillful but this is what you have to do. Growing up, when you think tennis is a given, you think you can work less. So I was very up and down. I would have good results here and then sleep for six months. And that's how I practiced, that was my lack of discipline as well.

I think when I got to Top 50, I got there with discipline. I just kind of veered off that course. So I think I still have a lot to give to tennis if my body holds. I don't feel 31.

I definitely think discipline is something I still owe to tennis and my career. Talent is nice but talent kicks in when discipline doesn't work anymore, and I tended to think the opposite. That's something I would do different.

Q: Coming back from your injury, how are you approaching your career now? 

When you get injured and you think you'll never play again, you realize what you've done wrong and you realize, "This is what I really regret and if I never play again, it will be my biggest regret."

I've gone through all that and now I think I'm definitely enjoying more. I'm judging myself less. I'll still always complain about things but that's me. But I try to do it to fire myself up instead of put myself down. I have opponents for that. I'm trying not to help that. So I think that changed.

I'm more focused now on process and tennis. I want to enjoy the way that I play regardless of whether I win or lose. That's definitely my main goal for the rest of my career.