Bay Area native suffers first doubles loss of year

   The doubles winning streak of Shuko Aoyama and Ena Shibahara ended with a thud tonight.

   Second-seeded Elise Mertens of Belgium and Aryna Sabalenka of Belarus routed seventh-seeded Aoyama and Shibahara of Japan 6-2, 6-0 in 53 minutes in the Australian Open quarterfinals in Melbourne.

   The 5-foot-1 (1.54-meter) Aoyama, 33, and Shibahara, a 22-year-old native of Mountain View in the San Francisco Bay Area, fell to 12-1 this year. They won titles in Abu Dhabi last month and Melbourne two weeks ago. 

   Aoyama and Shibahara were playing in their second Grand Slam quarterfinal. Aoyama also reached the Wimbledon semifinals in 2013 with Chanelle Scheepers of South Africa.

   Also tonight, third-seeded Barbora Krejcikova and Katerina Siniakova of the Czech Republic beat unseeded Sharon Fichman of Canada and Giuliana Olmos, a product of Fremont in the Bay Area who plays for Mexico, 7-5, 5-7, 6-2.

   Fichman, 30, and Olmos, 27, had never advanced past the second round in a major, separately or together, before this year's Australian Open.

   In the women's singles quarterfinals, third-seeded Naomi Osaka dismissed unseeded Hsieh Su-Wei of Chinese Taipei 6-2, 6-2 in 56 minutes.

   Osaka, the 2019 champion, will face 10th seed and seven-time champion Serena Williams, who dominated second-seeded Simona Halep 6-3, 6-3. Osaka is 2-1 against Williams, including a victory in the turbulent 2018 U.S. Open final. 

   Williams, 39, is making her 11th attempt to tie Margaret Court's record of 24 Grand Slam singles titles. Osaka made her WTA main-draw debut at age 16 at Stanford in 2014, when Williams won the last of her three titles there.

   In the men's singles quarterfinals, qualifier Aslan Karatsev of Russia beat 18th-seeded Grigor Dimitrov of Bulgaria 2-6, 6-4, 6-1, 6-2. Dimitrov, a three-time Grand Slam semifinalist, began suffering back spasms late in the second set and played half-heartedly the rest of the way.

   Karatsev, 27, became the first man in the Open Era to reach the semifinals in his Grand Slam main-draw debut. At No. 114, he is the lowest-ranked man to reach a major semifinal since Goran Ivanisevic at Wimbledon in 2001.

   Karatsev will face top-ranked Novak Djokovic, who outlasted sixth-seeded Alexander Zverev of Germany 6-7 (6), 6-2, 6-4, 7-6 (6), for the first time.

   Djokovic, seeking his third consecutive Australian Open title and ninth overall, suffered an abdominal muscle injury in his five-set victory over Taylor Fritz in the third round.