The first round clash had fallen victim to the rain that wiped out nearly all of Monday's schedule but after losing her first service game, fifth seed Hingis made short work of Olympic doubles champion Sun.
"I played really well," the 26-year-old Swiss told reporters.
"She started well and hit some good returns but I broke her back straight away and that gave me confidence."
In the next round Hingis will face Peng Shuai, China's strongest challenger at the $600,000 tournament in the absence of the injured Li Na and Zheng Jie.
"In the match against Peng, I should be ready from the first point not after the first game," joked Hingis, who is accompanied by her mother and one-time coach for the first time this year.
Peng, who lost to eventual champion Svetlana Kuznetsova in the semi-finals here last year, beat compatriot Xu Yifan 6-1 6-4 to claim her place in the second round.
"I don't think I played very well and I made a few mistakes but at least I won," said Peng, who is being coached by former French Open champion Michael Chang.
FIRST UPSET
Japan's Akiko Morigami caused the first upset of the tournament with her 6-4 6-4 defeat of seventh seed Anabel Medina Garrigues and will next face Aiko Nakamura, the 6-1 7-6 winner of another Hispano-Japanese clash against Lourdes Dominguez Lino.
Eighth seeded Greek Elena Daniilidou also wasted little time in dispensing with Belarussian Olga Govortsova 6-2 6-1 in their rain-delayed opener and will next face Lindsay Davenport or qualifier Julie Ditty for a place in the quarter-finals.
American Davenport astounded everybody by winning the Bali title last weekend on her return to competitive tennis after a year out of the game and just three months after giving birth.
The top four seeds -- Kuznetsova, Jelena Jankovic, Amelie Mauresmo and Elena Dementieva -- were all given byes through to the second round.
Kuznetsova admitted to being tired after losing the U.S. Open final and leading Russia to their Fed Cup triumph over the last two weekends.
"I just go out and play, not thinking about whether I will win or lose," she said.
"I think I have a good chance and I will try my best.
