The Smiling Assassin: Leylah Fernandez, 18, storms into maiden major quarterfinal at US Open

WATCH: Fernandez cites Roger Federer and Justine Henin among her inspirations.

NEW YORK—“Smiley” was Simona Halep’s first impression of a young Leylah Fernandez, who was understandably overjoyed at the opportunity to play doubles with a childhood idol at 16 years old.

“She’s smiling all the time,” Halep recalled at the Porsche Tennis Grand Prix in April.

On the edge of her nineteenth birthday, Fernandez is still smiling. She exchanges pleasantries with the US Open staff as she moves around the grounds. She shares trilingual social media posts in English, Spanish and French, and is a profound communicator for one still so young.

“From a very young age I'm just a happy-go-lucky girl,” she explained. “I never really take things too seriously, but I was just having fun on anything and everything that I do.

“I think sometimes the way that my parents would teach me off court, saying 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. But just the support of my family and of my sisters, they have definitely kept the joy for me.”

I expected that one day my tennis game is going to come through and that I'm going to be on the big stage in front of a big crowd playing against big players and also getting the wins. I'm not surprised of anything that's happening right now. Leylah Fernandez

Her earnestness, however, is not to be confused with naiveté; it has been Fernandez's decidedly underrated ferociousness—reminiscent of “Smiling Assassin” Martina Hingis—to carry her into a maiden major quarterfinal. Backing up a monumental upset over defending champion Naomi Osaka, Fernandez scored another on Sunday, this time over fellow lefty and former world No. 1 Angelique Kerber, 4-6, 7-6 (5), 6-2.

Though there’s a smoothness to the Canadian’s technique that one may trace back to Halep. Her southpaw style and unorthodox forehand grip, though, makes her a clear descendant of Kerber, who counterpunched her way to the US Open title in 2016. That they should meet in the round of 16 made for the ultimate generational clash and an intriguing contrast in disposition: Fernandez’s relentless positivity a foil to Kerber’s more brooding sarcasm.

“We have definitely watched her play a lot,” Fernandez confirmed, “especially used her as an example, the way she used her slice out wide and then go down the line right away on the open court, that she's definitely been an example for us. I tried to do that against her. I was glad that it worked.”

Still, Kerber has been on an upswing since her 13th career title at home in Bad Homburg, riding a 10-match winning streak into the Wimbledon semifinals—her first at a major since winning the All England Club crown in 2018. Staring at the teenager across the net, the German couldn’t help but feel some déjà vu.

“I think the serve and then the next ball after the serve,” Kerber said when asked to compare in press. “I think we played a little bit similar.

“She went out there, she played her tennis. She really is going for her winners, and, I think at the end it was just two, three points which decide the match. She took it in her hands.”

The match appeared very much in Kerber’s hands from the start as she reeled off four straight games to grab the opening set and soon moved ahead 4-2 in the second.

Fernandez, who won her first WTA title on hard courts in Monterrey in March, responded with just as she did against Osaka. Ostensibly on the brink of defeat, she broke back at love behind a flurry of winners and swept 12 of 15 points, foreshadowing an equally dominant stretch in the subsequent tiebreaker.

Racing ahead 5-1, she shook off some loose shots to overwhelm Kerber on set point, sneaking to net with a deft backhand volley.

Even without her ever-present father and coach, who opted to remain in Florida, Fernandez remained in full flight through the decider, saving a break point early on and two more as she served out the match—all three with forehand winners.

“He has his reasons, and obviously his reasons are working tremendously right now,” Fernandez said with a laugh.

Her “smiley” side came forth on the penultimate point of the match: in the midst of a titanic eighth game, she outrallied Kerber with the help of some audacious defense and athleticism—raising her fist to an enthralled Louis Armstrong Stadium having earned a match point.

“I was honestly tired in the third set, but with that thought, I was telling myself, like, If I'm tired, she must be exhausted,” she said of the 33-year-old Kerber.

On the precipice of a career breakthrough, she played Kerber’s own game to perfection, absorbing the German’s pace to ultimately draw the error and the roar of a crowd, one that has fallen for this fast-approaching cadre of talented teens—among them fellow 18-year-olds Emma Raducanu and Carlos Alcaraz, the latter of whom shared a photo-op with Fernandez earlier on Sunday.

“Seeing all these teenagers, the youngsters doing so great at the US Open and the other tournaments too is also eye-opening I think to the world, to the tennis world, because there is not only like one group of tennis players but there is a new wave of young generations that's coming up, and just trying to make an impact in the tennis game as much as they can.”

With two earth-shattering wins behind her, all her focus is on pulling off another as she prepares to play No. 5 seed Elina Svitolina for a spot in the semifinals. It would be an unreal achievement, but not one she believes is beyond her grasp.

“I expected that one day my tennis game is going to come through and that I'm going to be on the big stage in front of a big crowd playing against big players and also getting the wins. I'm not surprised of anything that's happening right now. I'm just glad that it's happening now and not later in the year, but we are just going to enjoy this time and take this one day at a time.”

Underestimate Fernandez at your peril; we may yet see her smile reflecting off the US Open trophy.