Ninth-ranked Agnieszka Radwanska of Poland coasted to a 6-1, 6-1 win over Japanese wild card Misaki Doi on Sunday in the first round of the Pan Pacific Open.
After struggling with her serve in the first set, Radwanska won 10 out of 10 points on her first serve in the second set to close out the match in 1 hour, 5 minutes at Ariake Colosseum.
"I was doing much better with my serve in the second set," Radwanska said. "I had some trouble with it in the first set but started hitting the ball better in the second set."
Defending champion Caroline Wozniacki of Denmark, the top-seeded player in the $2,000,000 tournament, has a first-round bye as does second-seeded Maria Sharapova of Russia.
In other first-round matches, 11th-seeded Anastasia Pavlyuchenkova of Russia beat Arantxa Rus of the Netherlands 6-4, 6-3.
Japan's Ayumi Morita advanced to the second round with a 7-5, 6-1 win over Irina Falconi of the United States. Thailand's Tamarine Tanasugarn opened with a 6-4, 6-4 win over Petra Cetkovska of the Czech Republic.
Israel's Shahar Peer recovered from a slow start to defeat wild card Kristyna Pliskova of the Czech Republic 4-6, 7-5, 6-1 while Britain's Laura Robson overpowered Alexandra Dulgheru of Romania 6-2, 6-2.