TOKYO-Former champion Petra Kvitova stormed through her opening match at the Pan Pacific Open on Tuesday, beating American Madison Brengle 6-3, 6-3 in a flurry of swashbuckling winners.

The 26-year-old Czech, twice a winner of Wimbledon, had too much firepower for Brengle in a match played under a closed roof due to typhoon rains in Tokyo. Seventh seed Kvitova will next play Rio Olympic gold medallist Monica Puig of Puerto Rico.

Meanwhile, sixth seed Dominika Cibulkova of Slovakia overcame another Czech, Lucie Safarova, 4-6, 6-1, 7-5 to set up a second-round match with fast-rising Japanese teenager Naomi Osaka. "I've seen her play a few times," Cibulkova said of Osaka. "She has a powerful serve and it's always tough playing against these young players -- they are fearless and have nothing to lose."

In other matches, Denmark's former world number one Caroline Wozniacki battled to a 6-2, 5-7, 6-1 victory over Switzerland's Belinda Bencic. Elsewhere on a day badly affected by the weather, Latvia's Anastasija Sevastova beat Ukrainian Kateryna Bondarenko 7-6, 6-3 while Aliaksandra Sasnovich of Belarus overcame Belgium's Yanina Wickmayer 3-6, 6-3, 6-3.

Jankovic marches through in o Guangzhou:  Defending champion Jelena Jankovic of Serbia sailed through her opening match at the WTA Guangzhou Open Tuesday, joining German Sabine Lisicki in the second round.

The 31-year-old former world number one eased past China's You Xiaodi 6-2, 6-1, while 2013 Wimbledon finalist Lisicki beat Kwan Yau Ng of Hong Kong 6-2, 6-0. China's Peng Shuai beat compatriot and eighth seed Zheng Saisai 4-6, 6-2, 6-3 and is scheduled to face Lisicki in the next round.

Jankovic will be confronting 21-year-old Swede Rebecca Peterson, listed as 124th in the WTA rankings. Twenty-year-old Estonian Anett Kontaveit made a strong showing, knocking out seventh seed Katerina Siniakova of the Czech Republic 6-1, 6-1 in a mere 54 minutes.

Begu sails into Korea Open second round: Top seed Irina-Camelia Begu on Tuesday sailed into the Korea Open second round with an overwhelming win over South Korean wildcard entrant Jang Su-Jeong. The 26-year-old Romanian, who is the world 23 and has won two titles at the Korea Open, ousted 186th-ranked Jang 6-2, 6-1 in 71 minutes in Seoul.

Begu is seeking redemption after suffering four consecutive first-round exits, including the Rio Olympics and the US Open, since winning the title at the WTA Florianopolis in July. Begu will next play Jana Cepelova from Slovakia. Second-seeded Johanna Larsson of Sweden defeated Grace Min of the US 0-6, 6-2, 6-2.

German teenager wins St Petersburg opener: German teenager Alexander Zverev, ranked 27th in the world, on Monday cruised into the second round of the St Petersburg Open with a straight-set win over Russian wildcard Karen Khachanov.

The 19-year-old fifth seed won his first ever meeting with Khachanov 7-6 (7/3), 6-4, as he targets his maiden ATP title. The German took the opening set in a tiebreak after 47 minutes before fighting back from 3-0 down in the second set to close out the match in one hour 25 minutes.

The Monte Carlo resident will now face the winner of the clash between Russians Daniil Medvedev and Alexander Bublik for a place in the last eight. "I was really nervous at the beginning as I didn't play for three weeks after the US Open," Zverev said. "Luckily, I then managed to find my rhythm and everything went fine for me."

Earlier, Ricardas Berankis of Lithuania, 83rd in the ATP rankings, ousted Frenchman Adrian Mannarino 7-6 (9/7), 3-6, 6-3 to set up a meeting with fourth seeded Spaniard Roberto Bautista Agut. Mannarino produced a catalogue of errors from the start but forced his way back from a break down to force a tiebreak, which the 26-year-old Lithuanian won. In the second Berankis was 2-0 up with an early break but Mannarino broke back twice to level at one set all.

The opponents traded breaks throughout the deciding set but Berankis edged it to claim the set and the match in two hours six minutes. "It wasn't that easy as my opponent performed a variety of shots making it difficult for me," Berankis said. "We were both up and down today but at the end I was a bit more lucky."

Lukas Rosol of the Czech Republic dropped serve twice but broke Argentina's Diego Schwartzman on five occasions in a 6-4, 6-4 win in 80 minutes. The 31-year-old will now meet top-seeded Swiss Stan Wawrinka, the freshly crowned US Open champion who enjoyed an opening-round bye.