Cincinnati, USA: Top seed Ashleigh Barty brushed aside Maria Sharapova in straight sets in her Cincinnati WTA opener on Wednesday, while Simona Halep also reached the third round.
Australia's Barty, 23, won the battle of former number one players in just over 90 minutes.
The reigning Roland Garros champion beat five-time Grand Slam winner Sharapova, who was Cincinnati champion in 2011, for the second time this season after a win at the Australian Open.
It was Barty's 40th victory of 2019 and she goes on to face Estonia's Anett Kontaveit, who beat Polish teenager Iga Swiatek 6-4, 7-6 (7/2).
"I did a really good job, especially in winning some of the crucial games," the Australian said.
"I love this time of year, getting back onto the hardcourts and back to the summer here."
Barty recovered after going down an early break to claim the opening set, before breaking Sharapova twice in the second to secure victory.
The winner fired 18 winners, breaking Sharapova four times as the Russian made 31 unforced errors.
Wimbledon champion Halep, seeded fourth, earned a late break in the penultimate game of the final set to beat Russian Ekaterina Alexandrova 3-6, 7-5, 6-4 after two hours on court.
The Romanian has finished runner-up in Cincinnati three times, last reaching the final a year ago against Kiki Bertens.
In the next round, the 27-year-old, who retired injured from her Toronto quarter-final against Czech qualifier Marie Bouzkova last week, will face either Madison Keys of the United States or Russia's Daria Kasatkina.
"It was a very, very tough match," Halep said. "She played well, hitting the ball very strong.
"Mentally, it was tough to return for me at the start after playing injured last week.
"But I didn't have pain, which is good. It took time to get a rhythm and then do something on court."
Halep went up a break in the third set, before letting the lead slip, only for the 43rd-ranked Alexandrova to serve two straight double-faults and fall 5-4 behind.
Halep completed her fightback on a second match point a game later.
"After the first set, I felt I could play aggressive," she added. "I also changed the tactics.
"I fought and did not give up. I wanted to run for every ball, it felt really good."
World number three Karolina Pliskova beat China's Wang Yafan 6-1, 6-3, while seventh seed Elina Svitolina, a semi-finalist four years ago, advanced past Belgian Elise Mertens 6-4, 6-1.
In the men's draw, fifth seed Stefanos Tsitsipas saved three match points but still lost to Germany's Jan-Lennard Struff 6-4, 6-7 (5/7), 7-6 (8/6).
Kei Nishikori lost to fellow Japanese Yoshihito Nishioka 7-6 (7/2), 6-4.
Sixth seed Nishikori has still never advanced beyond the third round in Cincinnati.
Ninth seed Daniil Medvedev, losing finalist to Rafael Nadal in Montreal last weekend, eased past Benoit Paire 7-6 (7/2), 6-1 and will next face Struff.
France's Richard Gasquet, who ended Andy Murray's comeback singles tournament in the first round, saw off Argentinian Federico Delbonis 7-5, 7-6 (7/1).
Australian Alex de Minaur defeated American Reilly Opelka 7-6 (7/3), 6-4 to set up a third-round tie with Nishioka.