The Czech left-hander, making her debut at the season-ender after a memorable year which has seen her rise to No.3 in the rankings this week, was romping away with it in the Sinan Erdem Dome until a second-set lapse slowed her progress.

From 1-4 in the second set Zvonareva rallied to break the Kvitova serve twice and level at 4-4 only to surrender her own serve again immediately.

Kvitova, 21, made no mistake as she served for the match, angling away a volley on her first match point to open her account in the round-robin format.

World number one Caroline Wozniacki was next on court against Poland's Agnieszka Radwanska, also in Red Group, while Blue Group play commences with Maria Sharapova, the only player who can topple Wozniacki from top spot, taking on US Open champion Samantha Stosur.

Istanbul is hosting the event, worth a staggering $4.9 million in prize money, for the first time after taking over from Doha for three years.

In St. Petersburg, Russia, fourth-seeded Marin Cilic of Croatia and American Alex Bogomolov Jr., seeded seventh, advanced to the second round of the St. Petersburg Open with straight-sets victories on Tuesday, while defending champion Mikhail Kukushkin of Kazakhstan made an early exit.

Bogomolov beat Igor Kunitsyn of Russia 6-3, 6-1, while Cilic ousted Ukrainian qualifier Sergei Bubka 6-4, 7-6 (1).

Bogomolov-who was making his debut at a second consecutive event in Russia after reaching the quarterfinals at the Kremlin Cup last week-broke Kunitsyn twice in the first set and three times in the second to win in 1 hour and 6 minutes.

"I know Kunitsyn and the way he plays perfectly," Bogomolov said. "It was important to neutralize his backhand. So, I served hard and returned with maximum concentration." Kukushkin, who was looking for his second title, was beaten by Michael Berrer of Germany 6-1, 4-6, 6-4. Julien Benneteau of France also advanced with a straight-sets victory over Pere Riba of Spain, 6-2, 6-1.

The 22nd-ranked Cilic is looking for his first title of the season. Cilic broke in the ninth game of the first set but Bubka saved five break points in the 11th game of the second set before the Croat prevailed in the tiebreaker to win on his first match point.

"It was really good for me to go through this match today," said Cilic, who reached the semifinals here four years ago. "Bubka was serving really good in some moments and especially in the second set on 5-all I had five break points and he served three aces and one service winner, so, it was really tough."

In Vienna, Tommy Haas rallied to beat fifth-seeded Juan Ignacio Chela of Argentina 6-7 (3), 6-3, 7-6 (5) Tuesday in the first round of the Erste Bank Open.

The 273rd-ranked German, who won the event in 2001, failed to serve out the match at 5-3 in the decider but converted his fourth match point in the tiebreaker.

Haas will next play Aljaz Bedene of Slovenia, who won the opening set against Ivo Karlovic 7-6 (4) before the Croat pulled out with a back injury.

Eighth-seeded Fabio Fognini of Italy advanced after Tommy Robredo of Spain retired with a left leg injury while trailing 7-6 (7), 5-7, 2-1.

Also, 2008 champion Philipp Petzschner of Germany routed Spain's Pablo Andujar 6-2, 6-2, and Daniel Brands of Germany defeated Martin Fischer of Austria 6-7 (3), 6-2, 7-6 (6).