Ex-world No. 1 to face current No. 1 in Australian Open

   Serena Williams continues to roll in a quest for a record-tying 24th Grand Slam singles title.
   Williams, a 37-year-old part-time resident of Silicon Valley, dismissed 18-year-old Dayana Yastremska of Ukraine 6-2, 6-1 in 67 minutes today in the third round of the Australian Open in Melbourne.
   The 16th-seeded Williams has not lost more than two games in a set in the tournament. The former world No. 1 will face current No. 1 Simona Halep, who dispatched Venus Williams 6-2, 6-3, for a quarterfinal berth.
   Serena Williams is 8-2 against Halep, including a Williams retirement.
   Fourth-seeded Naomi Osaka, the reigning U.S. Open champion, overcame 28th-seeded Hsieh Su-Wei of Chinese Taipei 5-7, 6-4, 6-1. Osaka, 21, of Japan trailed 4-1 (one service break) in the second set.
   Osaka will meet 13th-seeded Anastasija Sevastova of Latvia. Osaka beat Sevastova 3-6, 6-0, 6-4 two weeks ago in the Brisbane quarterfinals to even the head-to-head series 2-2.
   On the men's side, top-ranked Novak Djokovic beat 25th-seeded Denis Shapovalov, a 19-year-old Canadian, 6-3, 6-4, 4-6, 6-0.
   Djokovic, a six-time Australian Open champion, will play 15th-seeded Daniil Medvedev of Russia. Djokovic leads the head-to-head series 2-0.
   In the second round of women's doubles, ninth-seeded Raquel Atawo (Cal, 2001-04) of Sacramento and Katarina Srebotnik of Slovenia downed Margarita Gasparyan of Russia and Daria Gavrilova of Australia 6-2, 6-4. Both Gasparyan and Gavrilova were born in Moscow.