But looks can be deceiving when it comes to the 14th-seeded American.
The tenacious 21-year-old threw up her arms in frustration, yelled at herself and her box (which included 2009 Australian Open finalist Dinara Safina) and shrugged her arms demonstrably more times than one could count. She ran out of challenges in both sets, but that didn't stop her from jolting up her hand on almost every close point as her long earrings shook against her face with each moment of contention.
Kenin struggled at times with Jabeur's tricky shot selection, yet was always in control despite it being her first appearance in a major quarterfinal. She won 6-4, 6-4 in just over an hour-and-a-half before many unfamiliar tennis fans likely even had the chance to Google her.
But ready or not world, here comes Sofia, or Sonya, as her friends call her. Now with all the hopes of American tennis resting on her shoulders, she'll take on world No. 1 Ashleigh Barty in Thursday's semifinals. While many peers received the majority of the attention and excitement, it was Kenin who improbably came out of the most star-studded quarter of the draw to secure a spot in the final four. She'll become the second-ranked American behind Serena Williams in next week's rankings, and is the only woman or man from the United States remaining in singles play.
Having been handed her third loss by Kenin over the past year, Jabeur perhaps knows her game better than most. But for many fans of the sport, Kenin still remains a virtual unknown despite a stellar 2019 season.
"She's such an unbelievable player," Jabeur said after the match. "I had to run to every ball. She didn't give any free points. Not a lot of mistakes, which it was tough."
Kenin's past year reads like a fairytale and showcases one of the more meteoric, yet steady, rises one will see in professional tennis. Opening 2019 at No. 52, she won her first WTA singles title at Hobart, then won again at Mallorca and Guangzhou. She became the first American to beat 23-time Grand Slam champion Williams in a major since 2013 in the third round at the French Open in 2019 and credits that victory as a turning point.
"I feel like that was the first time I experienced getting to the second week," she said. "Obviously it felt really different. It's so much different.
"But, yeah, I feel like that match really changed things. I obviously saw that I can play on this level, I could play with the best. Of course, it just happened to be Serena, my idol. It was a really exciting match. I feel like after that, things took off."
She went on to win more hard-court matches (38) than anyone else. She qualified for the year-end WTA Elite Trophy event, as well as playing in one match at the WTA Finals as the second alternate. She took home two doubles titles (Auckland, Beijing) along the way.
By the end of the 2019 season, she was ranked a career-high No. 12 and was named the WTA's most improved player. Still, despite all she achieved in 2019, she has a relatively low profile and was largely overlooked entering the year's first Grand Slam. But it's hard to think that will happen again. She's dropped just one set (in a fourth-round tiebreaker to 15-year-old Coco Gauff) in her journey to the semifinals.
When her quarterfinal match was over, she clenched both of her fists and shook them while looking up at the sky. She breathed a sigh of relief but didn't smile. Only after she embraced her opponent warmly with a hug that lasted for several seconds did she appear to flash a grin. It was a markedly different response than when she beat Gauff -- another countrywoman who had massively outpaced her in the hype department -- two days prior, putting her head in her hands as she started to tear up.
"It feels really good," she said following her win over Jabeur. "I'm super excited for [the semifinals]. I think overall I played really good. I tried to handle the nerves. Obviously nerves coming into this match. I think I did a really good job handling myself.
"Celebration-wise wasn't as dramatic like the previous ones. Of course, I was even happier. I guess, I don't know, I just handled myself better overall. I feel like I'm playing really well. Of course, it's really different being second week in a semis. Obviously playing with more confidence. I really feel like I can do well."
While Gauff has been the young player to watch over the previous three Slams, and other up-and-coming Americans like Amanda Anisimova, Caty McNally and Danielle Collins have gotten their fair share of attention. In addition to the more-seasoned veterans in Serena and Venus Williams, Madison Keys and Sloane Stephens, Kenin proved focus and strong play are really all that matter.
"[It] goes to the stories that we have on the WTA at the moment that Sofia can be ranked 12 or 13 in the world and flying under the radar a little bit," said Darren Cahill, the ESPN analyst and coach of two-time major winner Simona Halep. "Kind of amazing. She's 21 years of age, she's a gun, a great player.
"She has that Simona fierce determination about her, as well. Great family. Her dad is a wonderful man. Kind of feels like he stresses through every point when he's watching on the outside. I'm stressing on the inside. He's stressing on the outside. So I kind of relate to what he's going through. I'm sure he's very proud of what Sofia's been able to do."
Born in Moscow and now based in Florida, she and her family moved to the United States when she was just a few months old. She started playing tennis at age 5, and her father, Alexander, was quick to recognize her potential. He remains her coach to this day. The father-daughter duo have an intense on-court rapport. But in an era where players seem to swap coaches more often than rackets, their longevity together seems to be working.
Kenin calls her life and the sacrifices her parents made for her "the American dream," and says off the court, she and her dad have a normal relationship that involves sightseeing and going out to eat while they are on the road for tournaments.
She hasn't minded the lack of attention or hype that many of her peers have received as of late, or even early in her career, because she's always had the unrelenting support of her family.
"I really had to establish myself to show everyone who I am," she said. "I think a big part that got me here is my family were there for me. It was obviously tough. People didn't really believe in me and everything.
"But [my family] believed in me, especially my dad since he's been with me through this incredible journey. I think that's obviously helped me. Obviously now I can see more people know me and it's a little bit different. I'm happy for that."
She describes her game as "aggressive," and says she like to dictate the points, but Chris Evert, the 18-time Grand Slam champion and current ESPN analyst, says her recent success is all part of a balanced game.
"Kenin is a great competitor," she said. "She's going to fight every point. She's a great counterpuncher. You know, she's got great defense, but that's not to say she's a pusher. She's still can play aggressively. She doesn't give any free points or unforced errors, and she's so good at absorbing pace."
The 14th player since 2000 to reach her first career Grand Slam semifinals in Melbourne, Kenin hopes to become the first one to advance to the final. Of course, she'll have her hands full with Barty, the reigning French Open and WTA Finals champion. Barty beat two-time major champion Petra Kvitova 7-6, 6-2 on Tuesday and is hoping to become the first Australian to win the singles title at the event since Christine O'Neil in 1978.
Barty, 23, owns a 4-1 career record over Kenin, but they've split their past two meetings at Toronto and Wuhan. Rennae Stubbs, the four-time major doubles champion, ESPN analyst and coach of Sam Stosur, called Kenin's win in Canada, "A huge win for her and she was just letting everybody know she's not afraid of anybody," while on air on Tuesday. Barty certainly knows their match will be anything but easy.
"[Kenin] loves to put herself out there, test herself on the biggest stage," Barty said. "She has a great knack of controlling the court from the center of the court and being that first-strike player. It's going to be important for me to try and nullify that if I can."
But while the odds, and the fans, are likely stacked against her, Jabeur still believes Kenin has a chance to win the title.
"Yeah, why not?" Jabeur said.
As for Kenin, she says she's just going to take it one match at a time, as she's always done.
"I mean, it would be amazing [to win the tournament]," she said with a smile. "But I'm just going to take it one match at a time. Whoever I play, of course, she's playing well.
"We'll just see how it goes. I mean, if you say it like that, if that happens, okay, I'm all in for that. I'll take it. Yeah, just one match at a time to not overthink things."