MELBOURNE－When Elise Mertens was growing up in the medieval city of Leuven, Belgium, Kim Clijsters and Justine Henin were taking the country's tennis to new heights.

Mertens remembers, when she was 5 years old, seeing Clijsters play for the first time－in 2001, the year the four-time Grand Slam winner made her first French Open final.

"I mean, what they achieved was amazing, and of course I looked up to them," Mertens said.

Now she is following in their sizable footsteps.

The 22-year-old Mertens upset fourth seed Elina Svitolina 6-4, 6-0 on Tuesday to reach the semifinals of the Australian Open, the first Belgian woman to do so since Clijsters' last appearance at the tournament in 2012.

Mertens has trained at Clijsters' academy in Belgium for the past three years and the pair have grown close. Clijsters has been watching all of Mertens' matches in Melbourne this week and texting her support.

"She was stressed in my last match," Mertens said in her on-court interview after beating Svitolina. "She said, 'Oh my God, I have so much stress.'"

And Mertens' game has clearly benefitted from Clijsters' mentoring, as well as her work with her coach and boyfriend Robbe Ceyssens, particularly in the past year as she's shot up the rankings.

Her rapid ascent began 12 months ago in Australia at a small tournament in Hobart that's held the same week as qualifying for the Australian Open.

Mertens and her second-round opponent, Sachia Vickery, were both entered in the qualifying event in Melbourne and needing to withdraw from Hobart, but Vickery retired from their match first.

With qualifying no longer an option, Mertens remained in Hobart and was soon rewarded with her first WTA title.

She also reached the third round of the French Open last year, and by the end of 2017, her ranking had jumped from No 120 to 35. Safely in the main draw for this year's Australian Open, Mertens returned to Hobart－and won the title again.

"I didn't really have a lot of expectations here (in Melbourne)," she said. "I played a qualifier in the first round, so I was expected to win. Not always easy but, yeah, as it moved forward, first round, second round, I didn't really expect to be in the semis."

Mertens has consequently been attracting quite a bit of attention－a new experience for a self-described "normal, quiet girl".

"She seems very strong mentally, moves well and doesn't have any weaknesses," 18-time major winner Martina Navratilova said. "Kim didn't have any weaknesses, did she? She knew how to play the game and I'm sure she's given Elise some good pointers. That always helps to get a champion's viewpoint."

Mertens' run is also testament to the unpredictability and newfound depth in the women's game, which has seen newcomers such as Jelena Ostapenko and Sloane Stephens come out of nowhere to win majors in the past year. First-time semifinalists have also broken through in 19 of the last 20 majors.

Mertens said seeing this has helped her believe that she, too, could contend for a Grand Slam title.

Now she's just two wins away, with second seed Caroline Wozniacki up next.

"I've got nothing to lose, that's for sure," Mertens said.

"I guess I'm a bit, well, the underdog, as of today. But I'm ready for it. I'm just going to give it my all and see where it ends."

AP