Former world number one Martina Hingis [ Images ] pulverised South Korea's Cho Yoon-Jeong 6-0, 6-0 in the Pan Pacific Open first round on Wednesday.

The Swiss returned to tennis last month and reached the Australian Open [ Images ] quarter-finals in her first Grand Slam since retiring through injury in 2002.

Hingis looked as though she had never been away, completely outclassing her Korean opponent in just 33 minutes.

A four-times Pan Pacific Open champion, Hingis will play third seed Nathalie Dechy [ Images ] of France [ Images ] in the last 16 of the $1.3 million (731,000 pound) tournament.

Earlier, second seed Elena Dementieva [ Images ] overcame an erratic start to beat Slovenia's Katarina Srebotnik 2-6, 6-1, 7-5 and reach the quarter-finals.

Dementieva had suffered a shock first-round exit at the Australian Open and the Russian was forced to work hard for her first victory of the year.

The world number nine will face Czech Nicole Vaidisova [ Images ] in the last eight after the fifth seed beat Japan's [ Images ] Saori Obata 6-4, 6-4.

Fifth seed Vaidisova plays Obata in a second-round match later on Wednesday.

Russian seventh seed Elena Likhovtseva overpowered Japan's Shinobu Asagoe 6-3, 6-2 in the first round.

In other matches, Lisa Raymond [ Images ] thrashed fellow American Meilen Tu 6-1, 6-3 to set up a second-round meeting with top seed and defending champion Maria Sharapova [ Images ] on Thursday.

Australia's [ Images ] Samantha Stosur [ Images ] breezed past Japan's Aiko Nakamura by the same score and next plays Slovakia's Daniela Hantuchova [ Images ].