By Alastair Himmer

TOKYO (Reuters) - Former world number one Ana Ivanovic booked a spot in the second round of the Pan Pacific Open on Monday and says she still has the game to challenge for grand slam titles.

"That's the only reason I'm still here," Ivanovic, who climbed to the top of the women's rankings after winning the 2008 French Open, 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. Otherwise I wouldn't be here," added the 24-year-old, the winner of 11 WTA Tour titles.

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

Ivanovic, seeded 11th, beat Andrea Hlavackova 6-3 2-0 to advance when the Czech retired with a thigh injury after just 44 minutes.

The Serb who reached the U.S. Open quarter-finals earlier this month, faces Urszula Radwanska in the second round after the Pole beat Japan's Kurumi Nara 6-2 6-4 .

France's Marion Bartoli 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, left the court fuming at a boisterous fan, glaring back at the seats as she walked to the net to shake hands with ninth seed Bartoli.

"I was told there was a drunk fan," said Date-Krumm, who shouted angrily in the direction of the spectator after netting a forehand during an attempted fightback.

"It was a big game and a big point. You're focusing so hard and it's extremely disappointing when people who are meant 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 China's Peng Shuai 6-1 6-4, ousting one of three Chinese taking part despite a fierce political row between China and Japan over disputed islands.

In other first-round matches, qualifier Pauline Parmentier beat fellow Frenchwoman Alize Cornet 6-3 6-4, while American Jamie Hampton was another qualifier to advance, ousting France's Caroline Garcia 6-2 6-2.

(Editing by Peter Rutherford)