TOKYO, JAPAN - SEPTEMBER 24: Caroline Wozniacki of Denmark serves in her first land match against Bojana Jovanovski of Servia during day two of the Toray Pan Pacific Open at Ariake Colosseum on September 24, 2012 in Tokyo, Japan. (Photo by Koki Nagahama/Getty Images)

Tokyo - Former world number one Caroline Wozniacki squeezed through to the second round of the Pan Pacific Open, just one day after ending a 13-month title drought in South Korea.

The Dane made hard work of beating Serb qualifier Bojana Jovanovski 6-0 3-6 6-4 in a match halted for an hour in the third set by lightning flashes and torrential rain.

Nine of the world's top 10 women are competing in Tokyo this week at the $2.16 million event, with the leading eight seeds receiving byes into the second round.

Wozniacki, who captured the Korea Open on Sunday, powered through a first set played in a warm breeze before fatigue hit her in the second.

The heavens broke at 3-3 in the decider and Wozniacki, down 15-30, eventually dropped her serve after waiting for the roof to be closed and the waterlogged court to be mopped dry.

Normal service was quickly resumed, however, as the 10th seed took the next three games to wrap up victory in two hours 17 minutes after forcing Jovanovski into a wild backhand.

“I was very lucky the rain came at 3-3 in the third,” Wozniacki told reporters. “I was feeling tired and it gave me a little time to relax and get my body back together.”

Serb Ana Ivanovic, another former world number one who is seeded 11th this week, progressed by beating Andrea Hlavackova 6-3 2-0 when the Czech retired with a thigh injury.

Ivanovic, who reached the U.S. Open quarter-finals earlier this month, said she still had the game to challenge for grand slam titles.

“That's the only reason I'm still here,” Ivanovic told Reuters. “I already achieved two of my biggest dreams in winning a grand slam and being number one in the world.

“But I believe I can still be at the top level and winning grand slams,” added the Serb who topped the rankings after winning the 2008 French Open.

Ninth seed Marion Bartoli of France bundled out Japan's Kimiko Date-Krumm 6-1 6-4 - just four days before the local favourite's 42nd birthday.

Wildcard Date-Krumm, who won the title in 1995, kicked an advertising board and left the court fuming at a boisterous fan, glaring back at the seats as she went to shake hands with Bartoli.

“I was told there was a drunk fan,” said the Japanese who shouted angrily in the direction of the spectator after netting a forehand while threatening a late fightback.

“You're focusing so hard and it's extremely disappointing when people who are supposed to be supporting you are drunk and shouting when you hit the ball.”

Italy's former French Open champion Francesca Schiavone squeezed past Yaroslava Shvedova of Kazakhstan 4-6 7-6 6-4 to set up a second-round match with Australian Samantha Stosur.

Russia's Nadia Petrova overpowered Peng Shuai 6-1 6-4, ousting one of three Chinese taking part despite their country's fierce political row with Japan over disputed islands.

Zheng Jie beat American Vania King 6-3 6-4 while last year's French Open champion Li Na opens her campaign against Russian Anastasia Pavlyuchenkova on Tuesday. – Reuters