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Dita Alangkara
Belgium's Elise Mertens celebrates after defeating Ukraine's Elina Svitolina in their quarterfinal at the Australian Open tennis championships in Melbourne, Australia, Tuesday, Jan. 23, 2018. (AP Photo/Dita Alangkara)

MELBOURNE, Australia (AP) — A year after opting out of qualifying for the Australian Open, Elise Mertens has reached the semifinals in her debut at the season-opening Grand Slam.

Mertens upset fourth-seeded Elina Svitolina 6-4, 6-0 on Tuesday to extend her winning streak to 10 matches and be the first woman through to the semifinals at Melbourne Park.

She's the first Belgian since Kim Clijsters in 2012 to reach the semifinals in Australia, and knew she had plenty of support at home.

"Kim, thanks for watching, I knew you sent me a message before the match — don't be too stressy," said Mertens, who trains at Clijsters' academy. "I'm trying to be in your footsteps this week."

The No. 37-ranked Mertens successfully defended her Hobart International title — she decided last year to target that title instead of entering Open qualifying — two weeks ago, and has now won five matches at Melbourne Park.

Mertens dominated against Svitolina, who also entered her first quarterfinal in Australia on a nine-match winning roll after winning the Brisbane International two week ago.

Svitolina had won their only previous tour-level match, but had no answers on Rod Laver Arena and later said hip trouble had been bothering her all year.

"She played great from the beginning of the year," Svitolina said. "But, you know, when I give her opportunities to play and to play a good level, then of course she's going to play. She's going to go for shots.

"Now she's in semifinal. Now she's not just a player that's up and down. She's quite consistent, and we can see this."

Mertens raced out to a 5-2 in the first set before Svitolina got her only service break. The second set was no contest. Mertens won a 27-point rally while holding serve in the fourth game, then hit a backhand winner into the open corner to break Svitolina in the next game for a 5-0 lead.

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Svitolina framed an attempted overhead and hit it over the baseline to give Mertens match point, and the 22-year-old Belgian duly finished it with a backhand crosscourt winner to advance to her first major semifinal.

Mertens was one of the biggest movers on the women's tour in 2017 as she improved her year-end ranking from 120 to 35 and won her first career title.

In the semis, she'll play either second-seeded Caroline Wozniacki or Carla Suarez Navarro.

In other quarterfinals, top-seeded Rafael Nadal was playing No. 6 Marin Cilic and No. 3 Grigor Dimitrov faced Kyle Edmund.