MELBOURNE, Australia — 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.
‘‘If you believe in yourself, then anything can happen,’’ she said. ‘‘But of course semis is, ‘Wow.’ ’’
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’s 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 weeks ago.
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.
Svitolina framed an attempted overhead and hit it over the baseline to give Mertens match point, and the 22-year-old Belgian 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 news, No 32-seeded Mischa Zverev was fined $45,000 for a poor performance in his first-round match against Hyeon Chung, the largest penalty ever assessed to an individual during a major.
Zverev was punished under a new rule implemented by the Grand Slam Board in the offseason intended to deter players with pre-existing injuries to start a tournament and retire from their first-round matches.
Under the rule, called ‘‘First Round Performance,’’ players can be levied a fine up to their first-round prize money if they do not ‘‘perform to a professional standard’’ in their match.
Zverev was trailing Chung, 2-6, 1-4, on the first day when he retired. His fine of $45,000 nearly equals his first-round prize money of $47,900.
If injured players withdraw before the tournament begins, however, they are still eligible to receive half of their first-round prize money. The players replacing them in the field — ‘‘lucky losers’’ who failed to advance out of the qualifying rounds — will get the other half, plus whatever they might accumulate by winning matches.
Zverev’s fine was the largest ever assessed to a player for an on-site Grand Slam offense. Other players have been fined larger amounts following a Grand Slam tournament, such as Serena Williams’ $82,500 fine in 2009 for her tirade at a US Open line judge.
Italian player Fabio Fognini was fined $96,000 last year after insulting a chair umpire at the US Open, an amount that could be reduced to $48,000 if he doesn’t have any further offences over the next two years.
The new rule came in response to a rash of first-round retirements at Wimbledon last year. Among those who pulled out were the opponents of Novak Djokovic and Roger Federer, both of whom retired with pre-existing injuries in back-to-back matches on Centre Court in under 45 minutes.
Australia’s Bernard Tomic finished his first-round match — a straight-sets loss to Zverev — but was later fined $15,000 for unsportsmanlike conduct for saying he was bored during the match and couldn’t find any motivation to compete.
. . .
Even by Australian Open standards, back-to-back shockers have resulted in a most unexpected quarterfinal.
The season-opening Grand Slam has a tendency to be unpredictable, but losing six-time champion Novak Djokovic and fifth-ranked Dominic Thiem within a few hours Monday leaves Hyeon Chung and Tennys Sandgren playing for a spot in the semifinals.
The 58th-ranked Chung relentlessly attacked a clearly injured Djokovic in a 7-6 (7-4), 7-5, 7-6 (7-3) fourth-round victory, becoming the first South Korean to reach the last eight at a Grand Slam.
Then there’s Sandgren. The 26-year-old from Tennessee had never won a Grand Slam match or beaten a top-10 player until last week. The 97th-ranked Sandgren beat Thiem, 6-2, 4-6, 7-6 (7-4), 6-7 (7-9), 6-3, following up on his victory over 2014 Australian Open champion Stan Wawrinka.
Sandgren’s only the second man in 20 years to reach the quarterfinals in his debut at Melbourne Park.
The bespectacled Chung ripped 47 winners, including a forehand on the slide and at full stretch that put him within two points of victory, and credited Djokovic as his inspiration.
‘‘When I’m young, I’m just trying to copy Novak because he’s my idol,’’ Chung said. ‘‘I can’t believe this tonight. Dreams come true tonight.’’
Djokovic was playing his first competitive tennis since Wimbledon last July, and had to remodel his service swing to take some load off his injured right elbow.
He winced and grimaced throughout the match, particularly when stretching for backhands, and needed a medical timeout in the second set for massage on his injured elbow.
The 12-time major champion said he would need to assess the injury, but didn’t want his pain to detract from Chung’s win.
‘‘Amazing. Amazing performance,’’ said Djokovic, who was seeded 14th after his ranking slid in 2017 while he was off the tour. ‘‘Whenever he was in trouble, he came up with some unbelievable shots. Just from the back of the court, you know, he was like a wall.’’
Chung was coming off a win over fourth-seeded Alexander Zverev, and is on a roll.
Djokovic wasn’t even sure until the last minute that he would be able to play at Melbourne Park, but was fit enough to beat Donald Young, Gael Monfils, and No. 21 Albert Ramos-Vinolas. Chung was a different proposition.
‘‘I had similar situations in the past where I found myself struggling a little bit with some injuries during the match, then I managed to win,’’ Djokovic said. ‘‘I felt the level of pain was not that high that I need to stop the match, even though it was obviously compromising my serve.
‘‘That’s life. I have to move on.’’
The 26-year-old Sandgren missed a match point in the fourth set, but held on to beat Thiem.
‘‘I don’t know if this is a dream or not — all you guys are here, so maybe it’s not,’’ Sandgren said in an on-court TV interview after his win. ‘‘I’m not in my underwear, so maybe it’s not a dream.’’
He described it later has ‘‘a real ‘pinch-me’ moment.’’
Sandgren converted half of his eight break-point chances, and fended off 10 of the 12 he faced against Thiem. He hit 63 winners against 38 unforced errors.
‘‘Trying to keep riding the wave,’’ said Sandgren, who was given his first name in memory of his great-grandfather.
Defending champion Roger Federer, meanwhile, had no real difficulties in reaching the quarterfinals for the 14th time.
He beat Marton Fucsovics 6-4, 7-6 (7-3), 6-2 and will next renew a lengthy rivalry against Tomas Berdych, who had a 6-1, 6-4, 6-4 win over Fabio Fognini.
The win over Fucsovics was Federer’s first day match of the 2018 tournament, and he joked about needing sunglasses and a towel for the beach, but said really the only change was to set the alarm for a different time.
Angelique Kerber, the only Grand Slam singles champion remaining in the women’s draw, was at work earlier than Federer, and got a serious wakeup call.
For a while it appeared former the Australian and US Open champion’s tournament could unravel against No. 88 Hsieh Su-wei, a former top-ranked doubles player with a double-handed grip on both sides.
Kerber recovered for a 4-6, 7-5, 6-1 win that earned her a quarterfinal spot against US Open finalist Madison Keys, who beat No. 8 Caroline Garcia, 6-3, 6-2.
‘‘Credit to her. She played an unbelievable match,’’ said Kerber, who is on a 13-match winning streak. ‘‘I was feeling I was running everywhere.’’
Top-seeded Simona Halep, who had to rally from triple match point down to advance through the third round, beat Naomi Osaka, 6-3, 6-2.
Halep will next play sixth-seeded Karolina Pliskova, who rounded off Day 8 with a 6-7 (5-7), 6-3, 6-2 win over No. 20 Barbora Strycova.