Ukrainian teenager Dayana Yastremska caused a major upset as she knocked out Australian Open champion Sofia Kenin from the Qatar Total Open yesterday. At the Khalifa International Tennis and Squash complex, the 19-year-old Yastremska served 13 aces and saved four of six break points to beat America Kenin 6-3, 7-6(4). 
It is Yastremska’s fourth Top 20 win of the season and she will face Muguruza in the third round after the Spaniard made short work of Australian Ajla Tomljanovic, winning 6-1, 6-2. For Kenin, it was her third defeat since winning her maiden Grand Slam title in Melbourne last month. 
The world number five lost one of her two matches in the United States’ Fed Cup qualifying win over Latvia, before being knocked out by in-form Kazakh Elena Rybakina in the Dubai opening round last week. “It’s really frustrating,” the 21-year-old said. “Obviously coming off of Melbourne where I felt I was playing the best tennis of my life, coming down to playing, not the worst tennis, but not playing the tennis I want to be playing,” he added.
“Creds to her, she played well, came up with some good shots at those important moments,” Kenin said of Yastremska, who has already won three WTA titles. “She just played better at important moments and I just made too many unforced errors, I just felt pretty flat-footed the whole match.”
Kenin conceded managing the expectations that come from winning her maiden major in Melbourne has been a challenge. “That’s what I got to figure out how to manage the expectations and people talking from the outside. But before Australia and everything obviously there was different kind of pressure, but I did have like expectations, I was hard on myself. I want to do well in every tournament, so it’s not a surprise. And nothing’s changed from my side the way I am, because I hate losing and, yeah, you know I hate losing,” she said.
Meanwhile, world number one Ashleigh Barty strolled past German Laura Siegemund in her first match since losing in the Australian Open semi-finals to Kenin. The reigning French Open champion saw off the world No 68, 6-3, 6-2.
Barty broke serve five times in the match, winning in under an hour and a quarter. “Happy overall to be able to switch on when I really needed to,” said Barty. “Disappointing to have a few lapses in concentration but also a credit to my opponent, she came up with some really good stuff in runs to be able to break me a few times.”
The Australian will next face Rybakina, who has already reached four WTA finals this season and beat Alison Van Uytvanck 5-7, 6-2, 7-6 (10/8) yesterday. The 20-year-old Rybakina, who lost to Simona Halep in the Dubai Championships final on Saturday, needed five match points to get past the Belgian, and also saved one herself in the marathon third-set tie-break. The world number 17, who was ranked 193rd 12 months ago, has now claimed a tour-leading 21 wins this year. 
Two-time Wimbledon champion Petra Kvitova also booked a place in the last 16 with a 4-6, 6-3, 6-0 win over Spaniard Carla Suarez Navarro. The Czech will face former Roland Garros winner Jelena Ostapenko for a quarter-final spot after the Latvian’s 6-1, 6-2 thrashing of Barbora Strycova.
World number three Karolina Pliskova also secured a third-round place with comfort, beating American Bernarda Pera 6-3, 6-0.  Pliskova will take on Tunisia’s Ons Jabeur, who beat American Jennifer Brady next 6-4, 6-3.
Pliskova emerged virtually unscathed from several back-and-forth opening salvos to race through the contest, securing the win in just under 56 minutes on Centre Court. “I think the beginning was a little bit tough,” she explained after the match. “We both played well, there were a couple tough, long games, but then somehow it turned to be quite easy, especially the second set, she was missing a lot. But she’s maybe loss her rhythm a little bit, I thought I was serving well, playing quite fast, so that can happen, I think.”
Last year’s winner Elise Mertens saw her title defence come to an early end with a 4-6, 6-3, 6-2 loss to Yulia Putintseva. Kazakhstan’s Putintseva will next play fourth seed Belinda Bencic after the Swiss battled past Veronika Kudermetova 6-4, 4-6, 7-6 (7/4).
Belarusian ninth seed Aryna Sabalenka also progressed, beating Anett Kontaveit 7-5, 2-6, 7-5.

2nd round Results 
(x denotes seeding):
Ashleigh Barty (AUS x1) bt Laura Siegemund (GER) 6-3, 6-2; Elena Rybakina (KAZ x14) bt Alison Van Uytvanck (BEL) 5-7, 6-2, 7-6 (10/8); Garbine Muguruza (ESP x11) bt Ajla Tomljanovic (AUS) 6-1, 6-2; Dayana Yastremska (UKR) bt Sofia Kenin (USA x6) 6-3, 7-6 (7/4); Karolina Pliskova (CZE x3) bt Bernarda Pera (USA) 6-3, 6-0; Jelena Ostapenko (LAT) bt Barbora Strycova (CZE) 6-1, 6-2; Petra Kvitova (CZE x8) bt Carla Suarez Navarro (ESP) 4-6, 6-3, 6-0; Svetlana Kuznetsova (RUS) bt Iga Swiatek (POL) 6-2, 6-2; Yulia Putintseva (KAZ) bt Elise Mertens (BEL x16) 4-6, 6-3, 6-2; Belinda Bencic (SUI x4) bt Veronika Kudermetova (RUS) 6-4, 4-6, 7-6 (7/4); Zheng Saisai (CHN) bt Vera Zvonareva (RUS) 7-5, 6-1; Aryna Sabalenka (BLR x9) bt Anett Kontaveit (EST) 7-5, 2-6, 7-5