Naomi Osaka, making her Brisbane main draw debut, snapped a four-match losing streak to beat 6-3 6-2 Destanee Aiava and moved to the quarterfinals, while top seed Elina Svitolina will have to beat Aliaksandra Sasnovich in a rematch of last year's final to join her in the last eight.
Third seed Sloane Stephens’ first match on Pat Rafter Arena in five years ended with a bitter loss. The 2017 US Open champion succumbed 6-4 6-3 to Johanna Konta at the Brisbane International. Petra Kvitova just teetering on the edge of defeat, but she prevailed 6-7(6) 7-6(6) 6-3 in a three-hour, four-minute battle before a packed Show Court 2 over Danielle Collins who served for the match at 5-4 in the second.
The Czech booked a second-round meeting with Estonia’s Anett Kontaveit aiming to extend her 3-1 lead in their head to head series. Making her fourth appearance at Brisbane, where she was champion in 2011, Kvitova has started the season ranked inside Top 10 for the first time since 2016.
Collins, playing only her second career tournament on Australian soil against one of three former champions in the draw, erased two set points with a backhand winner and an ace to hold to 4-5 in the opening set in her bid for her second ever Top 10 win.
Collins forced a tiebreaker and saved three further set points, as Kvitova looked burdened by as many unforced errors. The American won five straight points from 3-6 to seal the first set. Currently ranked No.36, one place off career-high set on August 6, 2018, following San Jose quarterfinals run, the American served for the match at 5-4 and even gained a 30-0 lead, but an untimely double fault gave Kvitova a breakpoint and mishit a forehand to gift the Wimbledon champion the opportunity to level the set.
Once more, Kvitova took the early lead in the tiebreak, once more Collins fought back to recover from 4-6 to 6-6, but this time the Czech forced the decider with a fiery forehand to tie the match at one set all. And from there she never looked back, swinging freely on her way to 4-0 in the deciding set.
The contest was over. In their first-time meeting, Konta proved steadier throughout the one-hour, 52-minute affair against Stephens who suffered the eighth defeat in 16 clashes against British opposition. “That was a really tough match.
I think the first three games took about half an hour. I’m just very happy I was able to maintain my level consistently throughout,”
said Konta, who made the quarterfinals here last season. Stephens began sluggishly and was punished for a string of unforced errors.
Her only short respite came at 1-0 down in the second set when play was suspended for several minutes while a member of the crowd was treated for a medical issue. The former Australian Open semi-finalist claimed the 15th Top 10 win of her career, and first since beating then-No.2 Simona Halep at Wimbledon in 2017.
She will now face Australian world No.46 Ajla Tomljanovic in a rematch of their Brisbane showdown from the same stage last year, which the Brit won. Tomljanovic stormed back after losing the first set to beat Czech world No.31 Katerina Sinakova, 1-6 6-3 6-0.
“It’s always nice to win but I felt kind of scrappy all around,” Tomljanovic said after the victory over world No.31 Siniakova as the tournament's website reported. “I think I was a break down at 40-15 and it was like 26 minutes (into match) and I was like ‘oh, my God.
It can’t get worse than this’. I just kind of kept at it. I didn’t expect the third to be so kind of quick and easy.” Australian No.2 Daria Gavrilova, returning to Brisbane for the first time since 2015, wasn’t so lucky.
She bowed out 6-3 6-3 in her first-round clash with No.8 seed Anastasija Sevastova, who reached the semifinals here last season. Playing Brisbane on a career-high ranking of No.11 Sevastova took her 148th main draw victory and extended her six-match winning streak against Australian opponents, last tasting defeat at hands of Stosur at 2017 Doha.
Sevastova, who could overtake Kasatkina and break into Top 10 by lifting the title, will now face Harriet Dart in the second round. The winner will meet Osaka, as she won eight of ten close games against Aiava who saved a match point to Minella in the second qualifying round and upset No.43 Mladenovic to register the first Top 50 win of her career.
The Japanese has now won 55-straight matches when winning the first set: she has suffered a comeback defeat since her final match of the 2016 season in Tianjin when she lost to Kuznetsova in the quarterfinals.
WTA Brisbane - Second round
Naomi Osaka (JAP) d. [Q]Destanee Aiava 6-3 6-2
Lesia Tsurenko (UKR) d. [WC] Kimberly Birrell (AUS) 6-4 6-3
Johanna Konta (GBR) d.  Sloane Stephens (USA) 6-4, 6-3
[Q] Destanee Aiava (AUS) -  Naomi Osaka (JAP)
 Anastasija Sevastova (LAT) d. Daria Gavrilova (AUS) 6-3, 6-3
 Petra Kvitova (CZE) d. Danielle Collins (USA) 6-7(6), 7-6(6), 6-3
Ajla Tomljanovic (AUS) d. Katerina Siniakova (RTC) 1-6, 6-3, 6-0
Aliaksandra Sasnovich (BLR) - [Q] Anastasia Potapova (RUS) 6-4, 7-5
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