Leylah Fernandez has taken down another ex-champion at the U.S. Open…

The 18-year-old half-Ecuadorian Canadian tennis player, unseeded at this year’s event, won the last five games to eliminate 2016 title winner Angelique Kerber 4-6, 7-6 (5), 6-2 on Sunday at Flushing Meadows, proving that her earlier upset of defending champion Naomi Osaka was no fluke.

In the process, Fernandez has reached her first Grand Slam quarterfinal, and she did a day before her 19th birthday.

With grit and guile, plus a veteran’s poise in the face of big deficits against much more accomplished opponents, Fernandez is displaying strokes and a demeanor that left Kerber offering this assessment: “She can go really far in the next few years.”

Ask Fernandez for the secret to her success, and she repeatedly mentions two factors. One is being sure to enjoy her time on court. The other is support of family, because her father, who is from Ecuador, her mother, who is Filipino Canadian, and her sisters “have definitely kept the joy for me.”

She credits Dad — who coaches her and has been offering instructions in daily phone calls while back home, taking care of a younger sibling — and Mom — who is leading the cheers with other family members and Fernandez’s fitness trainer in courtside seats — with teaching a valuable lesson that has nothing to do with tennis.

They made sure to emphasize, Fernandez said, that “you can’t take things too seriously, you’ve got to be mature but at the same time just be a kid, let loose, have fun, eat chocolate when you want to, and just have fun, watch movies, go past your bedtime.”

Just as against Osaka in Arthur Ashe Stadium two nights earlier, Fernandez dropped the opening set against Kerber in Louis Armstrong Stadium, which was so full that would-be spectators were being turned away at the doors.

And just as against Osaka, Fernandez trailed in the second set: Kerber led by a break at 4-2.

Both times, the 73rd-ranked Fernandez managed to get folks in the seats on her side, exulting with every of her on-the-run, impossible-angle groundstrokes that added up to a 45-28 edge in winners.

Fernandez redirects opponent’s shots swiftly and seemingly with ease, sometimes dropping to a knee near the baseline to get the proper leverage. That’s a very similar style to the one another lefty, Kerber, used to reach No. 1 in the rankings and claim three Grand Slam titles.

Kerber, 33, has been playing well enough lately to get to the Wimbledon semifinals in July, but instead of that experience paying off, Fernandez figured the age difference worked in her favor as the contest stretched past two hours.

“I was honestly tired in the third set,” Fernandez acknowledged. “But with that thought, I was telling myself, like, ‘If I’m tired, she must be exhausted.'”

Still, in the last set, Kerber held a break point with a chance to go up 3-1. Fernandez erased that chance with a cross-court forehand winner. Kerber wouldn’t claim another game.

When it ended, Fernandez lifted her arms, then leaned forward to put her hands on her knees and smiled. She stood and patted her chest with her palm, while Kerber walked around the net to offer a clasp of hands and an arm around Fernandez’s shoulders.

“I remember the feeling really well,” Kerber said when asked about playing with the sort of loose-grip freedom Fernandez displays. “I mean it’s (a) few years ago. But of course, I mean, she has no pressure.”

Now Fernandez, who only once had been as far as the third round at a major tournament until now, will meet No. 5 seed Elina Svitolina in the quarterfinals.